Patent Number: 056378785
Section: description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention any scanning or curtain electron-beam generator having a capacity of 500 kW generating energy of between 3 MeV to 50 MeV can be used in practicing the invention. Electron-beam units of about 10 kW to about 500 kW are suitable. In a preferred embodiment, referring to FIG. 1, an electron-beam generator 10 of about 50 kW capacity and generating energy of about 5 MeV is utilized. Electrons from a source 11 in a vacuum chamber 12 emerge from a grid 13 and are accelerated across a vacuum gap. The electron-beam 14 generates scattered beams 14.sup.1 to irradiate gemstones (not shown) in trays 15 on an oscillating means 16. A cooling means 17 forces a coolant, preferably a fluid such as water through trays 15. In another embodiment spraying mechanisms 20 may be used to spray a cooling fluid onto the gemstones from above. In accordance with an embodiment of this invention, topaz stones are placed onto trays 15 which are generally manufactured from metal, preferably aluminum and which measure about 48.times.8.times.1 inches. The topaz stones are placed into the trays 15 to a depth of about 1/2 inch. The trays are placed onto the oscillator 16 and the circulation of coolant through the coolant means 17 is begun. The coolant may be recirculated through the system. Initiating an oscillating motion along a horizontal y-axis at a rate of about 5 to 20 feet per minute. Then directing electron-beam radiation produced by an electron-beam generator 10 having a power of about 50 kW at about 5 MeV to provide a total dosage of between about 4 to about 25 gigarads over a period of 24 hours. The electron-beam generator 10 also oscillates along the z-axis, i.e., a ninety degree displacement over the oscillating means 16 to provide uniform coverage over the entire topaz mass. The rate of oscillation is preferably about 1 to 4 feet per second. The oscillation of both the electron-beam generator 10 and the oscillating tray holder 16 permits a portion of the topaz mass to avoid electron bombardment momentarily and enables the topaz mass to cool. The rate of oscillation of the electron-beam generator 10 and the oscillating means 16 is not critical and varies with the type and size of stones as well as the power utilized. However, the oscillation should be such as to provide a uniform irradiation of the gemstones. The circulation of coolant is continued through the coolant means until the gemstones reach ambient temperature and removing the uniformly colored blue topaz devoid of stress cracking and having less electronic discharge. Any undesirable or extraneous shades of color are eliminated. The present invention adds or enhances the color of topaz from any and all sources and all forms of topaz including but not limited to rough and preformed stones, carved stones, polished and cut stones, as well as, previously irradiated topaz by sub-atomic particles. For example, irradiated topaz from prior art processes may yield greenish-blue or greenish-yellow blue or brown stones. The instant process will alter these undesirable tints and produce a more desirable product. Furthermore, neutron treated stones are susceptible to cracking and more sensitive to heat and electronic discharge. The process of the present invention avoids these defects. Preferably the size of the topaz ranges from 0.2 to 100 carats. The process of the present invention also can enhance the properties of other gemstones, such as diamonds, beryl, quartz, tourmaline, sapphires, dark pearls and other minerals by uniformly increasing their color intensity, avoiding stress cracking and reducing the amount of residual radiation induced by other methods. The process can be operated more economically thus other devices capable of generating electrons such as primary linear accelerators, Van de Graaff generators and betatrons and other devices which are considered too expensive for the treatment of gemstones. It should be clearly understood that certain obvious modifications will occur to those skilled in the art to which this invention pertains. However, such obvious modifications are intended to be within the scope and purview of the present invention herein, and the outer boundaries of the scope of the instant invention are intended to be limited and determined only by the scope of the claims appended hereto.