The Ostro Stone is a breathtaking example of nature’s brilliance and human craftsmanship. At a staggering 9,381 carats—nearly 2 kilograms—this flawless blue topaz holds the title of the largest of its kind ever discovered and cut. With its vivid blue hue, exceptional clarity, and monumental size, it stands as one of the most extraordinary gemstones in existence.
A Legacy in Blue
The Ostro Stone owes its name and discovery to Max Ostro, a British explorer and gemstone trader who unearthed the original rough stone in the Minas Gerais region of Brazil more than 30 years ago. Minas Gerais is world-renowned for producing some of the finest topaz and other gemstones.
After its discovery, the rough topaz was carefully faceted into a stunning oval gem that retains flawless clarity and unmatched color saturation, a feat that speaks to both the rarity of the raw material and the precision of the cutting process.
Display and Ownership
Today, the Ostro Stone is on permanent loan to the Natural History Museum in London from Maurice Ostro, Max Ostro’s son. A philanthropist and entrepreneur, Maurice chose to share this gemstone with the public to honor his father’s legacy and showcase one of the Earth’s finest natural treasures.
Though the stone’s value has not been officially disclosed, its size, clarity, and provenance make it priceless in the eyes of collectors and gemologists alike.
Why the Ostro Stone Is So Special
World Record Size: It is the largest faceted blue topaz of flawless quality known to exist.
Flawless Clarity: The stone has no visible inclusions, making it an exceptional example of topaz.
Deep London Blue Color: Its rich, saturated blue color is the result of both natural composition and expert treatment.
Cultural Importance: Beyond its gemological value, it is a piece of gem history tied to a family legacy and proudly displayed for public appreciation.
Where You Can See It
You can view the Ostro Stone in person at London’s Natural History Museum, where it is featured as part of their Treasures gallery, alongside other world-famous gems like the Aurora Pyramid of Hope and the diamond-studded Aurora Butterfly of Peace.
The Ostro Stone is more than just a gemstone—it is a story of discovery, heritage, and wonder. As the largest flawless blue topaz ever documented, it stands as a symbol of Earth's geological artistry and human dedication to preserving beauty. Whether you're a gem enthusiast or a casual museumgoer, the Ostro Stone is a must-see marvel of the natural world.