Sinhalite is a mineral with a hardness of 7 out of 10 on the Mohs scale of mineral hardness [?]. These Orthorhombicly structured gems are made of magnesium aluminum iron borate, their full chemical compound being Mg(Al,Fe)BO4.

Sinhalite is a magnesium aluminum borate, and is most commonly found as transparent honey-yellow to brown grains or pebbles with an orthorhombic crystal system.

It also appears as pale yellowish, yellow, brown, greenish-brown to black.

It occurs in contact metamorphic rocks that are rich in boron, among gneiss or granite where limestones are being replaced through contact with magmatic rock. But most gem sinhalite is found as alluvial pebbles, carried by flowing water from upstream down to riverbeds. It exhibits brown, green-brown colors when light is passed through it.

It only used to be found in Sri Lanka, but it also began to be found from Myanmar (Burma) since 1958. A transparent golden brown chatoyant variety with a silver eye was found from its main source, Sri Lanka.

Aside from Sri Lanka and Myanmar, it is also found in Tanzania and the USA.

Why was Sinhalite mistaken for Brown Peridot?

Before its identification in 1952, sinhalite was often misidentified as brown peridot due to similar optical properties. It wasn't until detailed analysis of specimens from Sri Lanka that it was recognized as a distinct mineral species.

Are all Sinhalites from Sri Lanka?

While first discovered in Sri Lanka (hence the name), small deposits have been found in Tanzania and Madagascar. However, Sri Lankan material remains the standard for quality and size.

Why is Sinhalite so rare in collections?

Its late discovery, limited sources, and scarcity of facetable material make it one of the rarer collector gems. Few specimens exceed 5 carats, and clean stones are exceptionally uncommon.

How can I identify genuine Sinhalite?

Sinhalite shows high birefringence, distinctive honey-brown to yellow-brown color, and strong pleochroism. Professional testing is often needed as properties can overlap with other brown gems.

What causes Sinhalite's color variations?

Colors range from yellow-brown to deep brown due to iron content. The most valued specimens show golden-brown hues with good transparency. Darker specimens are more common but less desired.

Is Sinhalite ever treated?

Unlike many gemstones, sinhalite is rarely treated. Its color is natural and stable. The main challenge is finding clean, facetable material rather than enhancing existing stones.

What determines Sinhalite value?

Value depends primarily on size, clarity, and color intensity. Given its rarity, any clean faceted stone over 2 carats is considered significant. Historical specimens from the original Sri Lankan discovery command premiums.

The specific gravity [?] for Sinhalite is 3.48, its refractive index [?] is 1.67-1.71, and its double refraction [?] is 0.038.

History

Before 1952, when it was found to be a unique gem altogether, sinhalite was known as brown peridot or brown chrysolite because it has similar properties and refractive index to peridot. It is still a rare mineral today, and for years was known only from the gem gravels of Sri Lanka, thus taking its name from "sinhala" (Ceylon) in Sanskrit, the country's old name.

Industrial Usages

Sinhalite is rarely cut as faceted gems. When faceted as a gem, it resembles yellow or brown chrysoberyl.