GIA Graduate Diamonds Practice Exam 2026 – The Complete All-in-One Guide to Master Your Certification!

Indicator minerals are minerals that crystallize at great depths alongside diamonds and are carried to the surface by the same geological conduit, typically a kimberlite pipe. They form in the mantle or deep crust and survive the ascent with the rock, so their presence near the surface signals a nearby diamond-bearing source. This makes them extremely useful in diamond exploration because sampling for these minerals helps locate potential diamond-bearing pipes before diamond recovery. The other terms don’t fit because marine deposits describe oceanic sediments, and cave mining or drift refers to mining methods or structures rather than minerals that indicate deep, diamond-forming sources.