KNOW THE GEM
TERMINOLOGY

The chemical properties or characteristics of gems are also intrinsic. They are important to the expert, for one thing, as an aid in determining whether a gem is genuine or a fraud. The average consumer probably has little knowledge of chemistry beyond its bare bones, if that. For example, you probably do not care that a diamond is pure carbon or that a sapphire is aluminum oxide. Thus, the chemistry of gems will be left to the experts and will be mentioned only insofar as it has any pertinency to the other intrinsic characteristics.

Weight is intrinsic in one sense. Although gems come in many sizes and weights, experts speak of the specific gravity of gems, meaning the ratio of the weight of a stone (regardless of size) to an equal amount of water. As with the chemistry of gems, however, specific gravity is important only to an expert as a test to make sure what gem a gem is, since every gem has its own specific gravity.

The average person is neither an expert nor amateur gemologist nor mineralogist who will be able to identify a particular stone as being a diamond or a zircon. We count on the jeweler for that. However, technology plays an important role in detecting the genuine from the fraudulent. Consider the case of two of the most famous gems in the British crown jewels.

The Black Prince's Ruby has belonged to the British crown since it was given to Edward, the Black Prince, son of Edward II I, by Pedro the Cruel, who was placed on the throne of Spanish Castile by the Prince in 1367. Because rubies were supposed to protect their wearers from injury, the ruby was incorporated in the helmet worn by Henry V at the Battle of Agincourt in 1415.