Emerald

 Emerald wholesales to the trade today for approx. $40 for a 1 cwt stone of very low grade quality to approx. $7,000 for  a one carat example of extra fine quality. The price goes up to approx. $10,000 or more per cwt. for extra fine larger examples. The retail price will be several times that, depending on the retailers markup.   

Emerald is the gem stone for May and is said to aid peace of mind . Part of the Beryl family. The green colour comes from traces of Chromium and/or sometimes Vanadium. 7.5 to 8 on the mohs scale. Emerald is what is known as a type three gem, and as such it is very rare to find one without inclusions. 
Emeralds have been used as ornamentation for thousands of years. The huge Bahia Emerald is valued at $400,000,000.00.
In 2017 the 18.04 Rockefeller Emerald sold for $ 5,500,000.00 million at auction.