Patent Number: 050849093
Section: summary

BACKGROUND OF THE INVENTION The present invention relates to processing gemstones to enhance their color, and in particular, to color enhancement through gamma ray bombardment. In the early 1970's, Joe Borden and Charles Key produced and marketed sky blue topaz stones which had been subjected to electron bombardment. The color of these stones varied from light blue through extremely intense shades which could not be distinguished in appearance from California Blue. They also produced and marketed a small number of topaz gemstones with extremely dark colors, even to the point of showing some greenish and greyish overtones. The color of the gemstones depended upon the source of rough topaz and the dose of radiation. Each stone was found to have a color saturation point beyond which further irradiation would not enhance the color or would not be cost effective in further enhancing the color. The size of such sky blue topaz stones that could be produced was severely limited by the ability of 8-17MEV electrons to penetrate more than approximately three-quarters of an inch of topaz, the ability of the topaz to dissipate heat at the rate of energy applied, and the size of container used to allow forced circulation of water for cooling the stones during irradiation. Also in the early 1970's, Romanelle & Associates perfected the neutron irradiation of topaz gemstones in Britain to create "London Blue". These gemstones had a very dark color, which sometimes had a grey or green cast, making such gemstones less marketable. Messrs. Borden and Key experimented with some of this inferior London Blue product by bombarding it with electrons, and thus became the first to produce "California Blue" (aka Super Blue, Electra Blue, American Blue). The cost of buying London Blue gemstones from Romanelle was high and the cost of Brazilian rough which would produce intense sky blue colors was still low, so they made limited use of their invention. During the 1970's and early 1980's a great deal of misleading and incorrect information relating to gemstone irradiation was published in the trade journals. Dr. George Rossman at Caltech, the GIA, and others elsewhere began research in the field in the mid 1970's, but no one was able to actually explain the source of blue colors which formed in topaz. By 1984 or early 1985, a product similar to, but not necessarily the same as, California Blue was being produced by Zimmerman in Germany and marketed in the USA. Several different qualities of blue color abounded in the trade, all with the appellation "Swiss Blue". Stones from some sources had the appearance of California Blue, but from other sources they merely looked strong in blue with some greyishness. During the 1984-1985 time frame, I received some dark greyish London Blue stones from a customer of my ongoing gemstone color enhancement service (United Radiant Applications) and was asked to improve the color, which I did by repeating the former experiment of Messrs. Borden & Key, using electron irradiation to produce "California Blue" topaz. Prior to this I had established the use of heat, both to lighten London Blue that was over-irradiated and to eliminate some of the greenish or greyishness in bad batches and had offered heat treatment of London Blue Topaz as a service to my customers. Thus, heating either before or after the application of electron bombardment was naturally used to help the process along. I found that some types of London Blue topaz were very stubborn, having to be heated very much hotter and longer than other types to lighten color or remove undesirable tints. Some required only one hour (approx. 800 MR) of electron bombardment, but others ten hours. (approx. 8000 MR). I immediately recognized the commercial importance of Borden and Key's experiment, because, unlike theirs, my principal occupation was treating gems for customers. Market conditions had changed so that poorly colored London Blue was inexpensive and heavily discounted relative to the better product. So I began at once to offer to produce "Super Blue", as it was then called, from poorly colored London Blue. However, approximately two weeks later, Richard Fournier did the same experiment at the irradiation lab I also used. As he had begun in the early 80's to produce large amounts of London Blue, he was able to take much greater immediate commercial advantage of the process with his own material. The lab that Fournier and I used had recently opened a new linear accelerator facility, and the arrangements for irradiating topaz were changed from those formerly used. SUMMARY OF THE INVENTION The present invention adds and/or improves the color of topaz, tourmaline, diamonds, quartz, beryl and other minerals, by a process different than those heretofore used. The purpose of the process is to enhance the value of gemstones by increasing or decreasing their color intensity to that which is considered more "rare" or marketable and which cannot be done in any other way because of the size of the stones, fragility due to flaws or prior treatment, their thickness, shape, geometry, or the excessive residual radiation which could be induced by other methods. The process may be used to produce "normal" sky blue and the very desirable intensified "California Blue" (aka "Super Blue", "Electra Blue", "American Blue"). The present invention provides a method of processing gemstones for color enhancement by use of gamma rays in combination with heat, chemical treatment, other forms of radiation by subatomic particles, ion bombardment either prior to or subsequent to the application of the gamma flux. I have invented: a) a new and better method of producing California Blue from neutron irradiated topaz; b) a new and better method or finished condition, without the grey cast normally associated with Co60 irradiated stones, and of deeper color than the Co60 is capable of producing; c) a new and better method of color enhancing very large rough crystals, carvings or other finished forms of tourmaline quartz and beryl and other gems such that the colors obtained are more uniform throughout pieces of great thickness; d) a new and different method of color-enhancing any size rough or finished gems such as tourmaline and quartz which can produce a better color or a change in color and/or other physical properties, which is not accomplished by ordinary Co60 gamma rays, and which in and of itself or in combination with subsequent treatments renders the gemstone more valuable; e) a new and better method of producing California Blue and/or London Blue Topaz by irradiation with neutrons, protons and/or other subatomic particles and/or high energy gamma rays without the use of a nuclear reactor. It is an object of the present invention to produce a greater yield of exceptionally colorful stones, especially California blue topaz, by virtue of their size than materials irradiated with electrons only. Another object of the present invention to provide a fundamentally different method of processing London Blue topaz into California Blue which overcomes the limitations of size, placement in the radiation field, and which improves the recovery of unbroken stones. Thus, the present invention is superior in respect of economy as well as efficacy. It is a further object of the invention to provide an alternative and superior method of eliminating the steely-grey and/or green color from London Blue topaz and avoiding breakage during irradiation. A still further object of the present invention is to provide a method of producing sky blue and/or California Blue and/or London Blue topaz by irradiation with neutrons of energy much higher than those available in typical reactors or with protons of sufficient energy (and hence, range) to penetrate the particular the particular size gems. A benefit of using such high energy (3-300MEV) particles is the avoidance of extraneous activations by thermal or even the somewhat higher energy neutrons present in reactor irradiations. Even though the topaz may be colorless or light colored after such irradiation it can then be irradiated with gamma rays, to London Blue, or with electrons or higher energy gamma to produce sky blue or California Blue. An intermediate heating step may be used to anneal the topaz to improve its physical stability.