A Guide to Gemology

Gemstones include such stones as diamonds and sapphires. Those who are interested in gemology typically have a number of different things to consider, including those mentioned here.

General resources on gems include:
Gemstone Enhancement: provides information on the different types of enhancements done to gemstones.
Gemstones: offers information on classifying and grading gems.
Gemstone Characteristics: lists the hardness, family and other information on major gems.
Rock and Gemstone Collection: provides photographs of different sized and colored gems.
Gemstone Glossary: lists major terms used in gemology.

Gemstone Classification
Gemstones are classified in more ways than just by their color. Gemologists also look at the way light passes through the gem, the way it reacts to UV light and the clarity of the gem. The shape or system of the crystal is also important, with shapes including cubic and hexagonal.

Cutting and Polishing Gemstones
Gems are cut by using a slab or trimmer saw to shape it into the rough shape and size needed. Grinding and sanding is then done to the facets of the gem to shape it into the right size. After that, the gemologist polishes the stone by using a polishing agent such as aluminum oxide.

Gem Enhancements
Enhancements are defined as any type of work done on a gem to enhance its natural color. This includes heat treatments, oiling and irridation. Buyers should be careful about buying enhanced gems because some actually make the gems worthless or worth less than they would be otherwise.

Gem Substitutes
Gem substitutes range from paste pieces made to look real, to cheaper stones passed off as the real thing. Those who are new to the world of gemology should spend time handling the real thing and learning more before buying. This helps collectors see the look and feel of real gems compared to substitutes.

Reasons for Collecting Gemstones
There are a number of reasons why people might collect gems. Some do so because they like the look of a certain type, while others like the investment opportunity. There are even some who begin collecting because they like learning the history of different gems.

Do Gemstones Make Good Investments?
The answer to this question depends on the type of gem collected. While some remain popular for long periods of time, others are considered trendy because they only remain valuable for a short period of time. Those who want to use the gems as an investment should look for quality pieces with good clarity.

Caring for Gemstones
Caring for gemstones involves preventing damage. This is done by keeping the gems in cloth or velvet lined pouches and boxes and keeping the pieces from rubbing against each other, which can causes scratches. The cleaning of gems should be done by using a soft brush or cloth and jewelry cleaner.

Estimating the Weight of a Gem
It’s possible to estimate the weight of a gem even once it’s been set. Gemologists look at the size of the gem in relation to the setting and the part of the gem hidden by the setting. They also look at the shape of the gem, the cut and the thickness of the crown.

Rainbow of Gemstones
Emerald - marked by a bright shade of green.
Ruby - a bright shade of red.
Garnet - always a dark, deep shade of red.
Sapphire - a bright and dark blue.
Amethyst - a pale purple color.
Opal - typically contains shades of red, blue and green in the same gem.
Topaz - a variation of yellow or light brown.
Peridot - a bright green with flecks of gold.
Aquamarine - a pale blue color.
Tanzanite - bright blue with purple tones.
Citrine - a bright golden yellow.
Ametrine - contains shade of yellow and purple.
Crystal - varying colors with tiny bubbles beneath the surface.
Jade - green shades with an oily look.
Fire opal - has shades of red, yellow and orange.