(IDEX Online) - A ring with diamonds and a giant 8.11-ct pigeon's blood ruby - so-named because of its vivid crimson hue - is to be sold by Christie's Hong Kong with a high estimate of $4.5m.It will lead the Magnificent Jewels Auction on 28 November.The sale features additional high-value pigeon blood rubies - a pair of earrings with gems weighing 5.19-cts and 5.03-cts, and a high estimate of $4.3m.Such gems - with their exceptional saturation and natural red fluorescence - are becoming increasingly rare and valuable as the numbers being mined in Myanmar decrease steadily.Among other rarities in the sale are a ring and earrings with highly-prized Golconda diamonds from India. A 10.63-ct Golconda diamond ring has a $1.9m high estimate. Earrings totaling 5.10-cts and 5.02-cts could fetch up to $1.5m.Pic courtesy Christie's shows the pigeon's blood ruby ring