The superb clarity and color of the 37.8 carat Chalk Emerald ranks it among the world’s finest Colombian emeralds. According to legend, the Chalk Emerald was once the centerpiece of an emerald and diamond necklace belonging to a Maharani of the former state of Baroda, India. It was donated to the Smithsonian by Mr. and Mrs. O. Roy Chalk in 1972 and is on display in the Gem Gallery at the National Museum of Natural History.

One person had asked if these gems are replicas. They aren’t – they’re the real thing, part of the museum’s priceless gem collection. Some people may remember a gem exhibit I photographed at the Hillwood Estate, jewels previously owned by heiress Marjorie Merriweather Post. She had donated many of her pieces to the Smithsonian, and this is where they’re normally displayed.

Hope Diamond, posted earlier: