Rather than merely being one single mineral species, the garnet family consists of six fundamental sub-species with identical crystal structures. As a result, despite their differing compositions, the garnets tend to possess similar visual and physical attributes.

The three aluminum-containing sub-species are often classified together under the portmanteau “pyralspites”, with the abundant pyrope and almandine garnets possessing the dark red hues traditionally associated with the gemstone. However, spessartine is instead noted for its orangish coloration, with pure orange material sometimes sold under the trade name “mandarin garnet”.

The three remaining sub-species are termed “ugrandites”, and these all contain calcium within their fundamental compositions. While uvarovite’s bright green crystals are too small for mainstream jewelry use, similarly-colored grossularite (tsavorite) and andradite (demantoid) are amongst the best-known and most valuable of all green gemstones. In addition, yellowish, orangish, reddish and/or brownish grossularite (hessonite) is also commonly encountered within the marketplace.