At 2,475 carats (495 g), the Rajaratna Ruby is one of the world's largest ruby crystals, but is more of specimen than gem quality. An 18,696 carats (3.739 kg) crystal exists [1] and there is a 21,450 carats (4.29 kg) piece from Myanmar.[2] The "Chaiyo Ruby" is another large example, weighing 109,000 carats (22 kg).