How to Avoid Precious Stone Scams

Dealing with small objects of high value such as precious stones, it's not surprising to find there are a number of creative ongoing scams. The most obvious, of course, is simply to sell a less valuable stone in a more valuable rating. We have seen, in the case of diamonds, how even though subjective, a small difference in the rating can make a large difference in the price. Again, never buy mounted stones.

Substitution of less valuable stones is an offshoot of this where colorless topaz may be substituted for diamonds since most stones are colorless and have quite a bit of luster. The specific gravity of the topaz will approach that of a diamond. Of course, it won't pass other tests for a diamond.

Yellow quartz is often substituted for a yellow diamond. Red spinel is often offered for ruby. The worst examples of this occur in areas where the real stones are found.

Natural emeralds sold on the streets of Colombia, Peru and Brazil are often made from the bottoms of 7-Up bottles.

Sometimes diamonds are manipulated by taking a yellow diamond and super polishing it to look white. On occasion oil may be rubbed in to make it whiter.

Burma, India, Ceylon, Brazil, Peru and even Hong Kong and Thailand are notorious places for substitution of non-gem materials in gem sales.

Sometimes cut stones in upper and lower portions are cemented together. This is known as a doublet. It is possible to take two diamonds, the upper portion one and the lower of another and cement them together to create one diamond without the inherent flaws that the opposite piece had before the fusing process.

It is also possible, and is almost as common, to find the upper portion of a doublet is genuine while the lower portion is cut from a comparatively worthless material such as quartz or glass and then glued. If this is done with a great amount of skill, it will have the appearance of a single stone. It is legal to combine things such as diamonds, rubies, and sapphire doublets if they are not sold fraudulently.

The stone may be dropped in water or acetone and if it's a glued doublet, the glue will dissolve and the stone come apart. However, if glass has been used that's been fused to a diamond top, this will have no effect and the fusion must be found by careful, microscopic examination. This fraud is extremely difficult to detect.

A better test is to immerse the stone in a strong, refracting liquid such as methylene iodide. This is diluted until suddenly one part of the stone becomes invisible. This occurs when the refraction index of a liquid is the same as that of the stone and the quartz portion which has a much lower refraction number becomes invisible, leaving the diamond portion visible. This is an indication of a double stone. Indian jewelers are especially known for their production of such doublet stones.

For the extremely naive, it is possible to buy a false doublet. Here the color of the lower portion is imparted to the upper harder portion but neither party may be gem quality. This is when a piece of rock crystal quartz, a rather colorless stone, is used or glued to colored glass or colored stones. In this case, the top part will take on the color of the bottom part, although neither one is a gem stone. Extremely cheap doublets have been passed off by using simple colored gelatin or coloring and quartz or glass and a bit of glue.

Besides these tricks designed to use modified stone, there are scams such as examining a stone or piece of jewelry and having a second made to match and swapping the two. This can be done when someone goes to answer a newspaper ad, does not buy it but takes a picture or impression of it. Then his friend makes the phony and goes to "examine" the piece and switches the new for the old.

It may also be discovered a stone has been replaced with CZ after the piece was left for cleaning or appraisals.

Faked stones mounted in jewelry and then hocked is the oldest game in the world. The perpetrator runs out of money, offers to leave his precious ring as a security until he can get the money he borrows back to the person. The person may or may not skip with the stone, feeling he has the $5,000 ring.