A MODE OR PROCESS OF IMPROVING THE APPEARANCE OF INFERIOR QUALITIES OF DIAMONDS, RUBIES AND OTHER PRECIOUS STONES.
Year: 1882

page_text: LETTERS PATENT to John Clayton Mewburn of 169 Fleet Street in the City
of London Patent Agent and Consulting Engineer for an Invention of
A MODE OR PROCESS OF IMPROVING THE APPEARANCE OF INFERIOR QUALITIES
OF DIAMONDS, RUBIES AND OTHER PRECIOUS STONES. A communication to
him from abroad by Georges H. Durkés of Paris France.
PROVISIONAL SPECIFICATION left by the said John Clayton Mewburn at
the Office of the Commissioners of Patents on the 22nd November 1882.
JOHN CLAYTON MEWBURN of 169 Fleet Street in the City of London, Patent
Agent and Consulting Engineer "A MODE OR PROCESS OF IMPROVING THE
APPEARANCE OF INFERIOR QUALITIES OF DIAMONDS RUBIES AND OTHER PRECIOUS
STONES [A communication to him from abroad by Georges H. Durkés of Paris
France.]
The object of this invention is to improve inferior qualities of diamonds,
rubies and other precious stones, such for instance as sapphires, and the
invention as applied for example to diamonds consists in adding to this stone in
the manner hereinafter described the necessary complementary color to produce the
white color, the complementary color being in the form of an enamel glaze, and
being fixed as hereinafter explained.
In carrying out the invention I prepare the arrondi or girdle of the diamond by
submitting it to rough rubbing without polishing it, and I form it without facets.
I cover the surface of the arrondi or girdle thus prepared with a complementary
color of metallic enamel. I then enclose the diamond in a close vessel from which
all combustible gases such as oxygen have been removed by any ordinary process
such as burning in order to prevent the combustion of the diamond. I next
expose the close vessel to heat at the necessary temperature and for the necessary
time to enable the enamel to become fixed on the diamond by fusion. I then
allow the diamond to cool.

page_text: The color which is complementary to yellow in order to form the white color
being blue I employ blue to correct the yellow color of those diamonds or
stones which ought to be white and I thus produce what may be called azure
diamonds.
In the same way I employ for diamonds or other precious stones other
complementary colors, such as red for green or reciprocally in order to produce the
colors desired the complementary color being in all cases in the form of enamel
glaze which after being applied to the stone is fixed thereon as hereinbefore
described.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Clayton Mewburn in the Great Seal Patent Office on the
21st May 1883.
JOHN CLAYTON MEWBURN of 169 Fleet Street in the City of London Patent
Agent and Consulting Engineer A MODE OR PROCESS OF IMPROVING THE
APPEARANCE OF INFERIOR QUALITIES OF DIAMONDS RUBIES AND OTHER PRECIOUS
STONES (A communication to me from abroad by Georges H. Durkés of Paris,
France)
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The object of this Invention is to improve the appearance of inferior qualities of
diamonds, rubies and other precious stones, such for instance as sapphires, and the
invention as applied for example to diamonds consists in adding to this stone in
the manner hereinafter described the necessary complementary color to produce the
white color, the complementary color being applied by means of an enamel glaze as
hereinafter explained.
In carrying out the invention I prepare the arrondi or girdle of the diamond by
submitting it to rough rubbing without polishing it, and I form it without facets.
I cover the surface of the arrondi or girdle thus prepared with a complementary
color by means of an ordinary porcelain enamel or glaze such for example as
Rocaille glaze composed of 75 parts of minium and 25 parts of sand or a
compound glaze formed of 66 parts of minium, 22 parts of sand and 12 parts of
borax melted together. The glaze or enamel is applied to the diamond at as low a
temperature as possible by fusion. The fusion takes place in a close vessel filled
with inert gases, for example with carbonic acid gas produced simultaneously by
ordinary charcoal heated at the same time as the enamel to be fused. At this
moderate temperature the charcoal is converted into carbonic acid without the
diamond experiencing any change.
The color which is complementary to yellow in order to form the white color
being blue I employ blue to correct the yellow color of those diamonds or
stones which ought to be white and I thus produce what may be called azure
diamonds.

page_text: In the same way I employ for diamonds or other precious stones other
complementary colors such as red for green or reciprocally in order to produce the
colors desired, the complementary color being in all cases in the form of enamel or
glaze which is applied to the stone as herein before described.
Having now described the nature of the said Invention as communicated to me
and in what manner the same is to be performed I declare that I claim :-
The mode or process herein before described of improving the appearance of
inferior qualities of diamonds, rubies and other precious stones.
În witness whereof I the said John Clayton Mewburn have hereunto set my
hand and seal this twenty first day of May One thousand eight hundred
and eighty three.
J. C. MEWBURN (L.S.)