The Encyclopedia of Gemstones at gia.edu includes a wide variety of gems, such as topaz, diamond, emerald, aquamarine and rose quartz, as of 2015. In all, 29 different stones are featured. The full collection is sortable by color and nation of origin, with pictures displaying each stone in either its polished or rough state. A search bar is available for users who know exactly which stones they want to view.
In addition, the Encyclopedia of Gemstones includes amber, jade, amethyst, citrine and moonstone. One gem is "featured" periodically, serving as a kind of homepage for the entire encyclopedia. Gia.edu defaults to the Encyclopedia of Gemstones and includes a link back to it on the far left of the site's heading.
Each gem's entry includes trivia about the stone in question, chemical composition, possible colors and radioactivity, Mohs hardness, and specific gravity. Additional information is available in the mineral's description or history and lore sections. Every entry also includes a buyer's guide, which details where a gem could have come from, what sizes and colors are most desirable, grading criteria and a list of reputable dealers by ZIP code. There are also sections on imitations, synthetic knock-offs and treatments that improve a gem's look or make it last longer. All entries include a large gallery with multiple pictures of various specimens of a particular stone.
The Gemological Institute of America is responsible for the creation of the Encyclopedia of Gemstones. The organization also runs a private gem museum, a public library for research purposes, and provides grading and analysis services for all gemstones.