Crossword Help Forum
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1. Yellow Sapphire or yellow quartz gem
2. Ornament of precious metel often set with stones and worn as an accessory
3. May's birthstone
4. Small plane surface on a cut gem
5. Transparent blue gem
6. Transparent blue gem
7. Anagram of diopter (gem)
8. Anagram of singes (metamorphic rock)
9. Gem carved in relief
10. March's birthstone
11. The art of cutting gems
12. Rocks made from organic remains (shells coral)
13. June's birthstone
14. Small rounded stone worn down by water
15. Carving or inscription on rock
16. Method of searching for gold
17. Mineral used for insulation, removed because it causes cancer
18. anagram of tearing (igneous rock)

I think most 'crossword solvers' would prefer crossword clues to 18 questions about gems, no interlinking answers, we're told that some are anagrams... Sorry, it doesn't look like fun!

8-gneiss?
18 - granite
May birthstone could be emerald

Some of these could be found quite easily with Google and anagram solvers.
Sorry, I can't be bothered. I prefer crossword clues.