Lists of precious gemstones are provided by resources such as GemSelect, About.com and AJS Gems. These lists include pictures and additional information on the featured stones.
The list on GemSelect.com only contains natural precious gemstones; no man made stones are featured. Precious gemstones featured on this list include actinolite cat's eye, malachite and amethyst. Actinolite cat's eye is a rare form of chatoyant actinolite that has a translucent quality. It is commonly mistaken as "cat's eye jade." Malachite is a gemstone with a distinctive green color.
Amethyst is the most precious form of quartz, as of 2015. This stone ranges in color from pale lilac to a deep purple with hints of red. Additional stones featured on this list are onyx, beryl and boulder opal. Onyx is a black variety of chalcedony. Beryl is the parent mineral to gemstones such as emerald, aquamarine, heliodor and morganite.
Boulder opal is the second most valued opal variety. The name comes from the fact that it is found in ironstone boulders.
Gemstones featured on the list provided by About.com include agate, bloodstone, carnelian and garnet. Agate is a form of chalcedony that comes in a variety of colors. Bloodstone and carnelian are also varieties of chalcedony.