For every 10,000 gem-quality diamonds found, only one possesses brilliant and coveted color. Captivating and enigmatic, blue diamonds are considered the rarest of them all. A fabulous fluke of nature, a blue diamond is produced by the random presence of the atomic lattice-bound trace element boron within the stone’s carbon structure during its formation deep in the earth’s core.  

The earliest known blue diamond came from the legendary Kollur mine in the Golconda, a region of India that produced such famous examples as the Idol’s Eye (15th century) and the Hope Diamond (17th century), perhaps the most fabled gemstone on the planet. Today, blue diamond discoveries of any size are still sporadic and always astonishing occurrences. Ahead, view two blue diamonds on offer in Diamonds Online | Capsule Collection that are an extraordinary value, and revisit some of the other exceptional blue diamonds sold at Sotheby’s in recent years.