A massive emerald crystal was unearthed in the world’s largest emerald mine in Zambia in early October.

Geologist Debapriya Rakshit and experienced miner Richard Kapeta uncovered the impressive 5,655-carat emerald inside the largest open-pit mine in Kagem, which is partially owned by Gemfields — a London-based mining company. The gemstones inside the mine reportedly formed hundreds of millions of years ago.

The 5,655-carat Zambian emerald crystal has “remarkable clarity and a perfectly balanced golden green hue,” Gemfields described in a Monday news release.

It was spotted on Oct. 2 in the eastern part of the Kagem mine, where a team of miners has found luck in the past few months.

“This area of the mine has proven to be particularly fertile in recent months with the Kagem team recovering several significant crystals there, but none with the combined size, color and clarity of the Lion Emerald,” the mining company said.

Elena Basaglia, a Gemfields gemmologist, called the discovery an “important find” for the emerald world.

“We are experiencing strikingly increased demand for high-quality Zambian emeralds from the major brands, particularly in Europe, all of whom admire the rich color and unique transparency of our gems — qualities that make them unique among emeralds,” Basaglia said in an online statement. “It’s difficult to estimate how many individual gems will be cut from Inkalamu, but the cutting expertise of Gemfields’ auction partners will mean that this gemstone will make its mark in the history books of exceptional gemstones.”

Gemfields named the huge rock the “Inkalamu,” which translates to “lion” in the local Bemba language, to honor its 3-year partnership with non-profits the Niassa Carnivore Project and Zambian Carnivore Program.

“These partners work tirelessly to smooth the relationship between Africa’s carnivores and local communities across vast, remote and challenging areas. The health of carnivores, is widely regarded as a good indicator of the health of the wider eco-system due to carnivores’ status at the top of the local food chain,” Gemfields said.

The Lion Emerald will be put up for sale in Singapore in November.

“We expect a number of large, fine-quality cut emeralds to be borne of the Inkalamu crystal,” Adrian Banks, managing director for product and sales at Gemfields, said in a statement. “These important pieces are what return value to the buyer, and there might be hundreds of offcuts that are fashioned into smaller gems, cabochons and beads, but the key lies in recovering the fine quality pieces. Given this emerald is such a rare find, it is also perfectly conceivable that the buyer will choose to purchase it as an investment.”

While it’s a huge discovery, the Lion Emerald isn’t the biggest crystal to come from the Kagem mine. In 2010, Zambian miners retrieved a 6,225-carat emerald, which they dubbed “Insofu” or “elephant” for its size, The Telegraph reported at the time.