What are some seven-letter gemstones?

23 of the 170 gemstones in Icillion have exactly 7 letters, for example Diamond, Emerald and Peridot.

Which seven-letter gemstones start with A?

A is the most common first letter here, with 4 names, such as Abalone, Apatite, Axinite and Azurite.

Science · lists

23 seven-letter gemstones in alphabetical order, from “Abalone” to “Zoisite”. Each one counts as an answer in Icillion.

23 of the 170 gemstones have exactly 7 letters (14%).
Most start with A (4), E (4) and P (3).
Only names of one word are counted, and only their letters: spaces, hyphens and apostrophes are not.

What are some seven-letter gemstones?: 23 of the 170 gemstones in Icillion have exactly 7 letters, for example Diamond, Emerald and Peridot.
Which seven-letter gemstones start with A?: A is the most common first letter here, with 4 names, such as Abalone, Apatite, Axinite and Azurite.

How deep does your knowledge go?

Seven prompts a day, twenty seconds each. Obvious answers float on the tip of the iceberg; rare ones sink all the way to the trench.