Peridot engagement rings? Absolutely! Diamonds may be a girl's best friend, but Peridot engagement rings are a unique, original, and a far more affordable choice. Once considered more valuable than diamonds, a peridot ring is a must have. This "gem of the sun" is the birthstone of August and is a beautiful match for the lush green tapestry of late summer. Sapphire is the birthstone of September, and pink sapphire is a very popular gemstone in jewelry today. The bright and happy color of a pink sapphire ring is both playful and trendy.