In the late 19th century, corundum — ruby and sapphire — became one of the first gemstones created in laboratories to have the size and quality suitable for jewelry use. This Art Deco-style yellow gold ring, featuring a 6-ct synthetic ruby, is over 85 years old. Photo courtesy of liveauctioneers.com and Ultramax Auctions.
Credit: Ultramax Auctions
|Natural or man made||Lab-made|