<PAGE>


Lazare Kaplan Belgium NV                                                     1/9

                                    GUARANTY
                                   (Corporate)


New York, New York September 2, 1999


     FOR VALUE RECEIVED, and in consideration of loans made or to be made or
credit otherwise extended or to be extended by Antwerpse Diamantbank NV.
("Lender") to or for the account of Lazare Kaplan Belgium NV, Hoveniersstraat
30, 2018 Antwerpen, Belgium ("Borrower") from time to time and at any time and
for other good and valuable consideration and to induce Lender, in its
discretion, to make such loans or extensions of credit and to make or grant such
renewals, extensions, releases of collateral or relinquishments of legal rights
as Lender may deem advisable, the undersigned (and each of them if more than
one, the liability under this Guaranty being joint and several) unconditionally
guaranties to Lender, its successors, endorsees and assigns the prompt payment
when due (whether by acceleration or otherwise) of all present and future
obligations and liabilities of any and all kinds of Borrower to Lender and of
all instruments of any nature evidencing or relating to any such obligations and
liabilities upon which Borrower or one or more parties and Borrower is or may
become liable to Lender, whether incurred by Borrower as maker, endorser,
drawer, acceptor, guarantor, accommodation party or otherwise, and whether due
or to become due, secured or unsecured, absolute or contingent, joint or
several, and however or whenever acquired by Lender, whether arising under, out
of, or in connection with that certain Letter Agreement between Lender and
Borrower (as amended, supplemented, modified or restated from time to time, the
"Credit Agreement") or any documents, instruments or agreements relating to or
executed in connection with the Credit Agreement or any documents, instruments
or agreements referred to therein (together with the Credit Agreement, the "Loan
Documents"), or otherwise (all of which are herein collectively referred to as
the "Obligations"), and irrespective of the genuineness, validity, regularity or
enforceability of such Obligations, or of any instrument evidencing any of the
Obligations or of any collateral therefor or of the existence or extent of such
collateral, and irrespective of the allowability, allowance or disallowance of
any or all of the Obligations in any case commenced by or against Borrower
under Title 11, United States Code, including, without limitation, obligations
or indebtedness of Borrower for post-petition interest, fees, costs and charges
that would have accrued or been added to Borrower's Obligations to Lender but
for the commencement of such case. In furtherance of the foregoing, the
undersigned hereby agrees as follows:

     1. No Impairment. Lender may at any time and from time to time, either
before or after the maturity thereof, without notice to or further consent of
the undersigned, extend the time of payment of, exchange or surrender any
collateral for, renew or extend any of the Obligations or increase or decrease
the interest rate thereon, and may also make any agreement with Borrower or with
any other party to or person liable on any of the Obligations, or interested
therein, for the extension, renewal, payment, compromise, discharge or release
thereof, in whole or in part, or for any modification of the terms thereof or of
any agreement between Lender and Borrower or any such other party or person, or
make any election of rights Lender may deem desirable under the United States
Bankruptcy Code, as amended, or any other federal or state bankruptcy,
reorganization, moratorium or insolvency law relating to or affecting the
enforcement of creditors' rights generally (any of the foregoing, and
"Insolvency Law") without in any way impairing or affecting this Guaranty. This
instrument shall be effective regardless of the subsequent incoporation, merger
or consolidation of Borrower, or any change in the Composition, nature,
personnel or location of Borrower and shall extend to any successor entity to
Borrower, including a debtor in possession or the like under any Insolvency Law.








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Lazare Kaplan Belgium NV                                                     2/9

    2. Guaranty Absolute. The undersigned guarantees that the Obligations will
be paid strictly in accordance with the terms of the Credit Agreement and/or any
other document, instrument or agreement creating or evidencing the Obligations,
regardless of any law, regulation or order now or hereafter in effect in any
jurisdiction affecting any of such terms or the rights of Borrower with respect
thereto. The undersigned hereby knowingly accepts the full range of rights
encompassed within a contract of "continuing guaranty" which risk includes the
possibility that Borrower will contract additional indebtedness for which the
undersigned may be liable hereunder after Borrower's financial condition or
ability to pay its lawful debts when they fall due has deteriorated, whether or
not Borrower has properly authorized incurring such additional indebtedness. The
undersigned acknowledges that (i) no oral representations, including any
representation to extend credit or provide other financial accommodations to
borrower, have been made by Lender to induce the undersigned to enter into this
guaranty and (ii) any extension of credit to Borrower shall be governed solely
by the provisions of the Credit Agreement. The liability of the undersigned
under this Guaranty shall be absolute and unconditional, in accordance with its
terms, and shall remain in full force and effect without regard to, and shall
not be released, suspended, discharged, terminated or otherwise affected by, any
circumstance or occurrence whatsoever, including, without limitation: (a) any
waiver, indulgence, renewal, extension, amendment or modification of or
addition, consent or supplement to or deletion from or any other action or
inaction under or in respect of the Loan Documents or any other instruments or
agreements relating to the Obligations or any assignment or transfer of any
thereof; (b) any lack of validity or enforceability of any Loan Document or
other documents, instruments or agreements relating to the Obligation or any
assignment or transfer of any thereof; (c) any furnishing of any additional
security to Lender or its assignees or any acceptance thereof or any release of
any security by Lender or its assignees; (d) any limitation on any party's
liability or obligation under the Loan Documents or any other documents,
instruments or agreements relating to the Obligations or any assignment or
transfer of any thereof or any invalidity or unenforceability, in whole or in
part, of any such document, instrument or agreement or any term thereof; (e)
any bankruptcy, insolvency, reorganization, composition, adjustment,
dissolution, liquidation or other like proceeding relating to Borrower, or any
action taken with respect to this Guaranty by any trustee or receiver, or by any
court, in any such proceeding, whether or not the undersigned shall have notice
or knowledge of any of the foregoing; (f) any exchange, release or nonperfection
of any collateral, or any release, or amendment or waiver of or consent to
departure from any guaranty or security, for all or any of the Obligations; or
(g) any other circumstance which might otherwise constitute a defense available
to, or a discharge of, the undersigned. Any amounts due from the undersigned to
Lender shall bear interest until such amounts are paid in full at the highest
rate then applicable to the Obligation of Borrower to Lender under the Credit
Agreement. Obligations include post-petition interest whether or not allowed or
allowable.


     3. Waivers. (a) This Guaranty is a guaranty of payment and not of
collection. Lender shall be under no obligation to institute suit, exercise
rights or remedies or take any other action against Borrower or any other
person liable with respect to any of the Obligations or resort to any
collateral security held by it to secure any of the Obligations as a condition
precedent to the undersigned being obligated to perform as agreed herein and
Guarantor hereby waives any and all rights which it may have by statute or
otherwise which would require Lender to do any of the foregoing. The undersigned
further consents and agrees that Lender shall be under no obligation to marshall
any assets in favor of the undersigned, or against or in payment of any or all
of the Obligations. The undersigned hereby waives any and all suretyship
defenses and any rights to interpose any defense, counterclaim or offset of
any nature and description which it may have or which may exist









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Lazare Kaplan Belgium NV                                                     3/9

between and among Lender, Borrower and/or the undersigned with respect to the
undersigned's obligations under this Guaranty, or which Borrower may assert on
the underlying debt, including but not limited to failure of consideration,
breach of warranty, fraud, payment (other than cash payment if full of the
Obligations), statute of frauds, bankruptcy, infancy, statute of limitations,
accord and satisfaction, and usury.

     (b) The undersigned further waives (i) notice of the acceptance of this
Guaranty, of the making of any such loans or extensions of credit, and of all
notices and demands of any kind to which the undersigned may be entitled,
including, without limitation, notice of adverse change in Borrower's financial
condition or of any other fact which might materially increase the risk of the
undersigned; (ii) presentment to or demand of payment from anyone whomsoever
liable upon any of the Obligations, protest, notices of presentment, non-payment
or protest and notice of any sale of collateral security or any default of any
sort.

     (c) Notwithstanding any payment or payments made by the undersigned
hereunder, or any setoff or application of funds of the undersigned by Lender,
the undersigned shall not be entitled to be subrogated to any of the rights of
Lender against Borrower or against any collateral or guarantee or right of
offset held by Lender for the payment of the Obligations, nor shall the
undersigned seek or be entitled to seek any contribution or reimbursement from
Borrower in respect of payments made by the undersigned hereunder, until all
amounts owing to Lender by Borrower on account of the Obligations are paid in
full and the Credit Agreement has been terminated. If, notwithstanding the
foregoing, any amount shall be paid to the undersigned on account of such
subrogation rights at any time when all of the Obligations shall not have been
paid in full and the Credit Agreement shall not have been terminated, such
amount shall be held by the undersigned in trust for Lender, segregated from
other funds of the undersigned, and shall forthwith upon, and in any event
within two (2) business days of, receipt by the undersigned, be turned over
to Lender in the exact form received by the undersigned (duly endorsed by the
undersigned to Lender, if required), to be applied against the Obligations,
whether matured or unmatured, in such order as Lender may determine, subject
to the provisions of the Credit Agreement. Any and all present and future
debts and obligations of Borrower to any of the undersigned are hereby waived
and postponed in favor of, and subordinated to the full payment and performance
of, all present and future debts and obligations of Borrower to Lender.

     4. Security. All sums at any time to the credit of the undersigned and any
property of the undersigned in Lender's possession or in the possession of any
bank, financial institution or other entity that directly or indirectly, through
one or more intermediaries, controls or is controlled by, or is under common
control with, Lender (each such entity, an "Affiliate") shall be deemed held by
Lender or such Affiliate, as the case may be, as security for any and all of the
undersigner's obligation to Lender and to any Affiliate of Lender, no matter how
or when arising and whether under this or any other instrument, agreement of
otherwise.


     5. Representations and Warranties. The undersigned hereby represents and
warrants (all of which representations and warranties shall survive until all
Obligations are indefeasibly satisfied in full and there remain no outstanding
commitments under the Credit Agreement), that:


         (a) Corporate Status. The undersigned is a corporation duly organized,
validly existing and in good standing under the laws of the State of Delaware
and has full power, authority and legal right to own its property and assets and
to transact the business in which it is engaged.








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Lazare Kaplan Belgium NV                                                     4/9

         (b) Authority and Execution. The undersigned has full power, authority
and legal right to execute and deliver, and to perform its obligations under,
this Guaranty and has taken all necessary corporate and legal action to
authorize the execution, delivery and performance of this Guaranty.

         (c) Legal, Valid and Binding Character. This Guaranty constitutes the
legal, valid and binding obligation of the undersigned enforceable in accordance
with its terms, except as enforceability may be limited by applicable Insolvency
Law.

         (d) Violations. The execution, delivery and performance of this
Guaranty will not violate any requirement of law applicable to the undersigned
or any material contract, agreement or instrument to which the undersigned is a
party or by which the undersigned or any property of the undersigned is bound or
result in the creation or imposition of any mortgage, lien or other encumbrance
other than to Lender on any of the property or assets of the undersigned
pursuant to the provisions of any of the foregoing.

         (e) Consents or Approvals. No consent of any other person or entity
(including, without limitation, any creditor of the undersigned) and no consent,
license, permit, approval or authorization of, exemption by, notice or report
to, or registration, filing or declaration with, any governmental authority is
required in connection with the execution, delivery, performance, validity or
enforceability of this Guaranty.

         (f) Litigation. Except as set forth in the undersigned's current
report on Form 8-K filed with the United States Securities and Exchange
Commission (the "SEC") and dated April 13, 1999, no litigation, arbitration,
investigation or administrative proceeding of or before any court, arbitrator or
governmental authority, bureau or agency is currently pending or, to the best
knowledge of the undersigned, threatened (i) with respect to this Guaranty or
any of the transactions contemplated by this Guaranty or (ii) against or
affecting the undersigned, or any property or assets of the undersigned, which,
if adversely determined, would have a material adverse effect on the business,
operations, assets or condition, financial or otherwise, of the undersigned.

         (g) Material Adverse Change. Since February 28, 1999 which is the date
of the undersigned's most recent financial statement delivered to Lender there
has been no material adverse change in the assets or condition, financial or
otherwise, of the undersigned except as set forth in section 5 (f) above.

         (h) Financial Benefit. The undersigned has derived or expects to
derive a financial or other advantage from each and every loan, advance or
extension of credit made under the Credit Agreement or other Obligation incurred
by Borrower to Lender.

         (i) Financial Statements. The financial statements of the undersigned
have been prepared in accordance with United States generally accepted
accounting principles as in effect from time to time and present fairly the
consolidated financial position of the undersigned and its subsidiaries as of
the dates indicated therein and their results of operations for such periods;
provided, however, that the most recent interim financial statements are subject
to normal year-end adjustments and text footnotes and other presentation items.
The undersigned shall deliver to Lender, promptly upon their becoming available,
copies of any registration statements and any amendments and supplements
thereto, and any regular and periodic reports, if any, filed by the undersigned
with any securities exchange or with the SEC or any governmental authority
succeeding to any or all of the functions thereof, If the undersigned does not
file any such reports with any securities exchange or with the SEC or any
governmental authority succeeding to any or all of the functions thereof, then
the undersigned shall provide Lender with annual and quarterly financial
statements at such reasonable times as Lender requests.


         (j) Financial Condition. The undersigned is fully aware of the
financial condition of Borrower.









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Lazare Kaplan Belgium NV                                                     5/9

    The foregoing representations and warranties (other than that set forth in
paragraph (f) above) shall be deemed to have been made by the undersigned on the
date of each borrowing by Borrower under the Credit Agreement on and as of such
date of such borrowing as though made hereunder on and as of such date.

    6. Acceleration. (a) If any breach of any covenant or condition or other
event of default shall occur and be continuing under any agreement made by
Borrower to Lender beyond any applicable grace or cure period, or if any
material breach by the undersigned of any material covenant or condition
hereunder shall occur which shall remain unremedied for a period of thirty (30)
days after notice thereof shall have been given to the undersigned by Lender,
or either Borrower or the undersigned should at any time become insolvent, or
make a general assignment, or if a proceeding in or under any Insolvency Law
shall be filed or commenced by, or in respect of, the undersigned, or if a
notice of any lien, levy, or assessment is filed of record with respect to any
assets of the undersigned by the United States or any department, agency, or
instrumentality thereof, or if any taxes or debts owing at any time or times
hereafter to any one of them becomes a lien or encumbrance upon any assets of
the undersigned in Lender's possession, or otherwise, any and all Obligations
shall for purposes hereof, at Lender's option, be deemed due and payable
without notice notwithstanding that any such Obligation is not then due and
payable by Borrower.

     (b) The undersigned will promptly notify Lender of any obligations of the
undersigned becoming due prior to its stated maturity as a result of any default
by the undersigned in the performance or observance of any term or condition of
any agreement to which the undersigned is a party and, if such an event occurs,
Lender shall have the right to accelerate the undersigned's obligations
hereunder.

     7. Payments from Guarantor. Lender, In its sole and absolute discretion,
with or without notice to the undersigned, may apply on account of the
Obligations any payment from the undersigned or any other guarantor, or amounts
realized from any security for the Obligations, or may deposit any and all such
amounts realized in a non-interest bearing cash collateral deposit account to be
maintained as security for the Obligations.

     8. Costs. The undersigned shall pay on demand, all fees and expenses
(including reasonable expenses for legal services of every kind) relating or
incidental to the enforcement or protection of the rights of Lender hereunder or
under any of the Obligations.

     9. No Termination. This is a continuing irrevocable guaranty and shall
remain in full force and effect and be binding upon the undersigned, and the
undersigned's successors and assigns, until all of Borrower's Obligations have
been paid in full and the Credit Agreement has been terminated. If any of the
present or future Obligations are guarantied by persons, partnerships or
corporations in addition to the undersigned, the death, release or discharge in
whole or in part or the bankruptcy, merger, consolidation, incorporation,
liquidation or dissolution of one or more of them shall not discharge or affect
the liabilities of the undersigned under this Guaranty.

     10. Recapture. Anything in this Guaranty to the contrary notwithstanding,
if Lender receives any payment or payments on account of the liabilities
guarantied hereby, which payment or payments or any part thereof are
subsequently invalidated, declared to be fraudulent or preferential, set aside
and/or required to be repaid to a trustee, receiver, or any other party under
any Insolvency Law, common law or equitable doctrine, then to the extent of any
sum not finally retained by Lender, the undersigned's obligations to Lender
shall be reinstated and this Guaranty shall remain in full force and effect (or
be reinstated) until payment shall have been made to Lender, which payment shall
be due on demand.

     11. Books and Records. The books and records of Lender showing the










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Lazare Kaplan Belgium NV                                                     6/9


account between Lender and Borrower shall be admissible in evidence in any
action or proceeding, shall be binding upon the undersigned for the purpose
of establishing the items therein set forth and shall constitute prima facie
proof thereof.

     12. No Waiver. No failure on the part of Lender to exercise, and no delay
in exercising, any right, remedy or power hereunder shall operate as a waiver
thereof, nor shall any single or partial exercise by Lender of any right, remedy
or power hereunder preclude any other or future exercise of any other legal
right, remedy or power. Each and every right, remedy and power hereby granted to
Lender or allowed it by law or other agreement shall be cumulative and not
exclusive of any other, and may be exercised by Lender at any time and from time
to time.


     13. Waiver of Jury Trial. THE UNDERSIGNED DOES HEREBY KNOWINGLY,
VOLUNTARILY AND INTENTIONALLY WAIVE THE RIGHT TO TRIAL BY JURY IN ANY ACTION OR
PROCEEDING BASED ON OR WITH RESPECT TO THIS GUARANTY OR ANY OF THE TRANSACTIONS
CONTEMPLATED HEREBY OR RELATING OR INCIDENTAL HERETO. THE UNDERSIGNED DOES
HEREBY CERTIFY THAT NO REPRESENTATIVE OR AGENT OF LENDER HAS REPRESENTED,
EXPRESSLY OR OTHERWISE, THAT LENDER WOULD NOT, IN THE EVENT OF LITIGATION,
SEEK TO ENFORCE THIS WAIVER OF RIGHT TO JURY TRIAL PROVISION.

     14. Governing Law; Jurisdiction; Amendments. THIS INSTRUMENT CANNOT BE
CHANGED OR TERMINATED ORALLY, AND SHALL BE GOVERNED, CONSTRUED AND INTERPRETED
AS TO VALIDITY, ENFORCEMENT AND IN ALL OTHER RESPECTS IN ACCORDANCE WITH THE
LAWS OF THE STATE OF NEW YORK. THE UNDERSIGNED EXPRESSLY CONSENTS TO THE
JURISDICTION AND VENUE OF THE SUPREME COURT OF THE STATE OF NEW YORK, COUNTY OF
NEW YORK, AND OF THE UNITED STATES DISTRICT COURT FOR THE SOUTHERN DISTRICT OF
NEW YORK FOR ALL PURPOSES IN CONNECTION HEREWITH. ANY JUDICIAL PROCEEDING BY THE
UNDERSIGNED AGAINST LENDER INVOLVING, DIRECTLY OR INDIRECTLY ANY MATTER OR CLAIM
IN ANY WAY ARISING OUT OF, RELATED TO OR CONNECTED HEREWITH SHALL BE BROUGHT
ONLY IN THE SUPREME COURT OF THE STATE OF NEW YORK, COUNTY OF NEW YORK OR THE
UNITED STATES DISTRICT COURT FOR THE SOUTHERN DISTRICT OF NEW YORK. THE
UNDERSIGNED FURTHER CONSENTS THAT ANY SUMMONS, SUBPOENA OR OTHER PROCESS OR
PAPERS (INCLUDING, WITHOUT LIMITATION, ANY NOTICE OR MOTION OR OTHER APPLICATION
TO EITHER OF THE AFOREMENTIONED COURTS OR A JUDGE THEREOF) OR ANY NOTICE IN
CONNECTION WITH ANY PROCEEDINGS HEREUNDER, MAY BE SERVED INSIDE OR OUTSIDE OF
THE STATE OF NEW YORK OR THE SOUTHERN DISTRICT OF NEW YORK BY REGISTERED OR
CERTIFIED MAIL, RETURN RECEIPT REQUESTED, OR BY PERSONAL SERVICE PROVIDED A
REASONABLE TIME FOR APPEARANCE IS PERMITTED, OR IN SUCH OTHER MANNER AS MAY BE
PERMISSIBLE UNDER THE RULES OF SAID COURTS. THE UNDERSIGNED WAIVES ANY OBJECTION
TO JURISDICTION AND VENUE OF ANY ACTION INSTITUTED HEREON AND SHALL NOT ASSERT
ANY DEFENSE BASED ON LACK OF JURISDICTION OR VENUE OR BASED UPON FORUM NON
CONVENIENS.

     15. Severability. To the extent permitted by applicable law, any provision
of this Guaranty which is prohibited or unenforceable in any jurisdiction shall,
as to such









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Lazare Kaplan Belgium NV                                                     7/9

jurisdiction, be ineffective to the extent of such prohibition or
unenforceability without invalidating the remaining provisions hereof, and
any such prohibition or unenforceability in any jurisdiction shall not
invalidate or render unenforceable such provision in any other jurisdiction.

     16. Amendments, Waivers. No amendment or waiver of any provision of
this Guaranty nor consent to any departure by the undersigned therefrom shall
in any event be effective unless the same shall be in writing executed by the
undersigned and Lender.

     17. Notice. All notices, requests and demands to or upon the undersigned,
shall be in writing or by telecopy or telex and shall be deemed to have been
duly given or made (a) when delivered, if by hand, (b) three (3) days after
being deposited in the mail, postage prepaid, if by mail, (c) when confirmed, if
by telecopy or, (d) in the case of telex notice, when sent, answer back
receiver, in each event, to the number and address set forth beneath the
signature of the undersigned.

     18. Successors. Lender may, from time to time, without notice to the
undersigned, sell, assign, transfer or otherwise dispose of all or any part of
the Obligations and/or rights under this Guaranty. Without limiting the
generality of the foregoing, Lender may assign, or grant participations to, one
or more banks, financial institutions or other entities all or any part of any
of the Obligations. In each such event, Lender, its Affiliates and each and
every immediate and succesive purchaser, assignee, transferee or holder of all
or any part of the Obligations shall have the right to enforce this Guaranty, by
legal action or otherwise, for its own benefit as fully as if such purchaser,
assignee, transferee or holder were herein by name specifically given such
right. Lender shall have an unimpaired right to enforce this Guaranty for its
benefit with respect to that portion of the Obligations which Lender has not
disposed of, sold, assigned or otherwise transferred.

     19. Release. Nothing except cash payment in full of the Obligations shall
release the undersigned from liability under this Guaranty.









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Lazare Kaplan Belgium NV                                                     8/9

     IN WITNESS WHEREOF, this Guaranty has been executed by the undersigned
this 2nd day of September, 1999.

     Lazare Kaplan International Inc., acting a.o. through its Lazare Kaplan
Division, Preferred Diamonds Division, Scientific Division and Lazare Kaplan
(Puerto Rico) Division, Lazare Kaplan Africa Inc., Lazare Kaplan Europe Inc.,
Lazare Kaplan Japan Inc.

                                GUARANTOR


                                By Sheldon Ginsberg
                                   -------------------------------------
                                   Name  Sheldon Ginsberg
                                   Title Exec. V.P. and Chief Financial Officer

                                Address  529 Fifth Avenue
                                         New York, New York 10017
                                         USA

                                Telecopier No 212 697 3197
                                              ----------------------------









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Lazare Kaplan Belgium NV                                                     9/9

STATE OF NEW YORK  )
                   ):  ss.:
COUNTY OF NEW YORK )

     On the 2nd day of Sept., 1999, before me personally came Sheldon L.
Ginsberg to me known, who being by me duly sworn, did depose and say that
he resides at 529 5th Ave., New York, NY 10017, that he is the Executive VP
& CFO of Lazare Kaplan International Inc., the corporation described in and
which executed the foregoing instrument; that he knows the seal of said
corporation; that the seal affixed to said instrument is such corporate seal;
that it was so affixed by order of the board of directors of said corporation,
and that he signed his name thereto by order of said corporation.


                                    RUTH STOLL KASSANGA
                                    -------------------------------------
                                    Notary Public

                                    RUTH STOLL KASSANGA
                                    NOTARY PUBLIC, State of New York
                                    No. 31-4825046
                                    Qualified in New York County
                                    Commission Expires Dec. 31, 2000