Identifying Garnets Simplified

The most complicated part of identifying garnets is distinguishing between the species. The gems in the almandine, pyrope, and spessartite series are particularly difficult separations. However, the following chart will simplify the process once you’ve done your preliminary identification and are sure you’re dealing with a garnet stone.

Identifying Garnets Using Three Factors

You can use the refractive index (RI), hue, and absorption spectrum of your garnet specimen to make your identification.

Please note, density isn’t useful for distinguishing garnet species. There is too much overlap among their values. However, grossular is an exception. It has a maximum density of 3.66.

RI is useful for distinguishing pyrope and grossular, since their values are much lower than the rest. For identifying garnets of other species, you’ll need a combination of RI, hue, and absorption spectrum evaluations.

Species RI Hue Absorption
Andradite 1.880 – 1.895 Very slightly yellowish green through orangey yellow None except demantoid, which shows a cut off at 440-445 nm. May have bands at 618 and 634. Demantoid may have thin bands at 685 and 690.
Grossular 1.730 – 1.760 All colors, including colorless, except blue. None except highly saturated orange which show bands at

Premium Article

This is a Premium Article. Please become a member to read this entire article and gain access to hundreds more like it.

Membership options

Full Article Details

Content Length 445 words
Reading time 2 min 14 sec

Here's what you get if you unlock this article:

  • Identifying Garnets Using Three Factors

Plus, additional member-only benefits:

  • Exclusive access to other premium articles and courses
  • Unlimited access to our gem pricing guide
  • Participate in our member-only forums
Membership options