Spinel
The 170 ct "Black Prince's Ruby" worn by Henry V on his helmet at the Battle of Agincourt and was in fact a spinet.
Named “Balas Ruby” in the past, there was no distinction made between ruby and red spinel, as they were very similar. The most desirable spinel colour is a deep blood red, though blue, yellow, orange, pink and purple make fine gemstones. Spinels are highly collectable and a gem to invest in.
Cabochon spinel bangle