The extremely rare, 10-carat Mediterranean Blue diamond could fetch a whopping $20 million at Sotheby's High Jewelry auction ...
The stone appears green or blue in daylight or fluorescent light. In incandescent light, it is red or purple. The gem takes its name from Emperor Alexander II of Russia, the Geological Institute ...
Known for its deep red hue, rubies are highly prized and valued at around $4,625 per carat. One of the hardest and most sought-after gemstones, diamonds cost approximately $9,502.13 per carat. A light ...