Deep Blue; the Birthstone of September
This page is the CodyCross answer for the clue below from Inventions, Group 56, Puzzle 4.
Question is: Deep Blue; the Birthstone of September
and the answer is: SAPPHIRE
Word Meaning:
SAPPHIRE — (countable) A clear deep blue variety of corundum, valued as a precious stone.
Definitions from Wiktionary.