How to Look and Describe a Gemstone?

Glossary and Terms related Gemstones

One of the most important things in jewelry business, whether you are a customer or a jeweler, is to know how to look and describe characteristics of a gemstone. I am not talking about the observation part (using a loupe and all that) – we have already done that. I am talking about what you do after that – the inference part – how you describe what you saw in a gemstone, how compare the gemstone with other sets of observations, how you describe to a jeweler the gemstone of your dreams. For doing that, you first need to acquaint yourself with the terminology and conventions used in the gemstone trade.

So, first things first, we talk about a faceted gemstone in terms of various aspects and characteristics:
Girdle: It is the edge or perimeter of the stone, where the top portion and the bottom portion meet. This is where one should hold the stone, whether with bare fingers or a pair of tweezers.
Crown: this is the top of the stone – the part above the girdle.
Pavilion: this is the bottom portion of the stone – from the girdle to the vertex the stone converges to at the bottom.
Culet: this is the vertex that the stone converges to.
Table: the table, also know as the face, is the flat top of the stone. It is the largest facet of the stone.

Images Courtesy : Twin City Diamond

Gemstone Shapes and Cut

The next figure (Image Courtesy:Lapigems Gem Company) illustrates the classic shapes that gems are cut into. What shape of gemstone a particular customer chooses depends on his taste. Each gemstone shape has a look and feel of its own. However, the real thing that distinguishes good gems is the cut – the quality of workmanship. The precision with which the facets of the gemstone were sculpted and the proportion into which the gemstone was shaped decide its brilliance and its price for eternity.

Again, you will encounter a difference between diamonds and colored gemstones in this regard. In diamonds, if the material is of good quality (which can be graded in terms of color and inclusions), a good cut in terms of facets can make all the difference between a lively and brilliant stone and a completely dull and lifeless one. On the other hands, colored stones do not depend much on their cut for brilliance. The dimensions and the proportioning, however, are very important as they affect the depth of color of the gemstone, which in turn affects its brilliance.

To judge these qualities in a stone, jewelers generally look at the gemstone through the Table. This gives an idea as to whether the stone is well-centered (symmetric) or not, and whether or not the stone has a good hue from up there (this is decided by whether or not the stone is well proportioned throughout).

However, the following markers are to be used to form an opinion on the workmanship involved in a stone:

• The tone of the stone becomes darker as the cut goes thicker and the pavilion goes deep and broad.
• The tone of the stone goes lighter as the stone goes thinner, that is, the pavilion is more shallow and narrow.

So, in short, if the stone appears to be lively from the table (when you examined it as directed above), it means that the gemstone is more or less well-proportioned, no matter how thin or thick it appears to be. The physical proportions might have been set in accordance with the richness of the material of the gemstone.

Anyway, it’s the table view that is most important.