Where sapphire gets its blue tint mainly from iron, rubies get their pink to blood-red hue from chromium. So [NightHawkInLight]’s recipe starts with aluminum oxide grit-blasting powder and ...

pink and red to dusky grey, green and purple. Until they were properly identified in the 18th century, red spinels were called rubies; the 170-carat Black Prince’s Ruby at the front of the ...

“With the pink rubies from the Baringo area, these new rubies present some serious hope for the Kenyan gem industry as the stones we saw were of commercial to very fine facet quality ...