September’s birthstone, Sapphire, is one of the most beloved gemstones. Considered one of the “Big Three” (along with ruby and emerald),  sapphire stepped into the spotlight with Princess Diana’s famous engagement ring, which Prince William then bestowed to Kate Middleton when he proposed in 2010.

GIA’s Sapphire Buyers Guide provides the quick tips you need when shopping for one of these sought-after gems. Find out why color is the most important indicator of value, what “silk” means in reference to a sapphire, and which color sapphires are named “Padparadscha.”

Click the buying guide image to see a larger view. Bookmark and share!