The 37.8-Carat Chalk Emerald Is a Regal Example of May's Official Birthstone

A stunning representation of May’s official birthstone, the 37.8-carat Chalk Emerald stands out for its unparalleled combination of size, clarity, lush green hue and royal provenance.

This exquisite gemstone, now housed at the Smithsonian’s National Museum of Natural History in Washington, DC, boasts the deep, velvety green color that is the hallmark of the finest Colombian emeralds. The stunning stone — set in a lavish ring — can be seen alongside legends like the Hope Diamond in the museum’s prestigious National Gem Gallery.

The Chalk Emerald was unearthed near Muzo, Colombia, a region renowned for producing the world's most prized emeralds. Long before Spanish conquistadors arrived in the 1500s, Colombian emeralds were cherished by indigenous cultures for more than 1,000 years.

Following the Spanish conquest, these mesmerizing green stones quickly gained favor among European royalty and rulers across Asia, particularly the Mughal emperors of India, who helped fuel a robust gem trade between the New World, the Middle East and South Asia.

According to legend, the Chalk Emerald once adorned an opulent necklace belonging to a Maharani of Baroda, a princely state in India. Originally weighing 38.4 carats, the gem was acquired and recut by famed New York jeweler Harry Winston in 1959 to enhance its brilliance, resulting in its current 37.82-carat weight.

Winston then set the transformed emerald into a platinum and gold ring, surrounded by 60 pear-shaped diamonds totaling 15 carats.

New York entrepreneur Oscar Roy Chalk acquired the ring in 1962 for his wife, Claire. In a gesture of extraordinary generosity, the couple donated the piece to the Smithsonian in 1972, where it remains one of the museum’s most visited and admired treasures.

Emeralds, the most valuable variety of the beryl family, are renowned not only for their vivid color but also for their internal characteristics. These natural inclusions — affectionately called "jardin" (French for "garden") — are embraced by gemologists and collectors alike, as they give each emerald a distinct character and identity.

The word “emerald” traces its roots to the ancient Greek "smaragdos," meaning “green gem.” In addition to being May’s birthstone, emerald is also the traditional gemstone for 20th and 35th wedding anniversaries.

Whether admired for its royal past or dazzling beauty, the Chalk Emerald remains a crown jewel among gemstones — and a timeless tribute to the lush green brilliance of May’s birthstone.

Credit: Photo by Chip Clark / Smithsonian and digitally enhanced by SquareMoose.