Diamond is April's birthstone — and every natural diamond is a story billions of years in the making, told in light. At RARE.DIAMONDS we care most about one thing: precision cutting that brings out every bit of a diamond's brilliance. Here are some favorite short facts to help you see diamonds the way a cutter does.

What Makes a Diamond a Diamond?

• Hardest natural material: Diamond is 10 on the Mohs scale, which is why diamond is polished with diamond. Hard is not the same as unbreakable — a sharp blow can still chip a thin edge or a point.
• Ancient origin: Most natural diamonds formed roughly one to three and a half billion years ago, deep in the earth, and were later carried to the surface by volcanic eruptions.
• Yes, they can burn: Diamond is carbon. In air, at the temperatures of a fire or a jeweler's torch, its surface can burn. That is why stones are protected, or removed, during repairs that use heat.
• Color is a spectrum: Colorless diamonds are graded D to Z, from colorless to light yellow or brown. Natural fancy colors such as blue, green, orange, pink and red are far rarer; yellow and brown are more common.
• Carat is weight, not size: One carat is 0.20 grams (about 0.007 oz). How large a diamond looks face-up also depends on its shape and how it is cut.

From Deep Earth to Your Hand

• Where they form: Most natural diamonds formed roughly 90 to 120 miles (about 150 to 200 km) below the surface, under immense pressure and high temperature.
• How they travel: Deep-sourced eruptions through kimberlite and lamproite pipes carried the crystals upward; over time, rivers washed some of them into gravel deposits.
• Rarity in practice: Only a fraction of mined diamonds are gem quality — and an even smaller fraction are cut for the best possible optical performance. Read more in Understanding Rare Diamonds.

Famous Stones We Never Tire Of

• Cullinan: The 3,106-carat rough found in South Africa in 1905 was cut into nine major stones and about 96 smaller ones. Cullinan I and II are set in the British Crown Jewels.
• Hope Diamond: A 45.52-carat blue graded by GIA as Fancy Dark Grayish-Blue, with a long and storied past — now on display at the Smithsonian.
• Wittelsbach-Graff: A historic blue diamond whose color, like most natural blues, comes from traces of boron.

Discover more in our legendary diamonds guide.

Care Tips from the Bench

• At home: Warm water, a drop of mild detergent and a soft brush. Rinse well and dry with a lint-free cloth.
• At the jeweler: Ultrasonic and steam cleaning work well for untreated diamonds in secure settings — have the prongs and any pavé checked first. They are not advised for fracture-filled or treated stones, or diamonds with significant surface-reaching inclusions.
• Avoid buildup: Lotions, hair spray, cooking oils and sunscreen quickly dull the sparkle. Take rings off before applying them.

For the full guide, see Diamond Care & Maintenance.

America's Public Diamond Park

Crater of Diamonds State Park in Arkansas is a rare place where anyone can search a natural diamond-bearing deposit and keep what they find. Tens of thousands of diamonds have been found there since the early 1900s. The largest diamond ever found in the United States, the 40.23-carat "Uncle Sam," was found there in 1924, before the site became a state park.

A Note on Performance

Cut is the engine of beauty. When proportions, optical symmetry and polish come together, a diamond delivers brilliance, fire and scintillation that perform in real life, not just under showcase lighting. That is the standard we hold ourselves to. See the anatomy of the round brilliant to learn why.

Quick FAQ

Are diamonds indestructible?
No. They are extremely hard, but a sharp impact on a thin edge or a point can chip them. Treat them like fine optics.

Can diamonds burn?
Yes. At very high temperatures in air, diamond can burn. Normal wear is no risk, but tell your jeweler before any repair that uses heat.

How big is a 1-carat diamond?
It weighs 0.20 grams. How large it looks face-up depends on shape and cut; a well-cut round balances face-up size with light performance.

What makes a diamond look "whiter"?
The color grade matters most, but precise cutting increases brightness and contrast, which can help a diamond look whiter face-up.

Where do fancy colors come from?
Traces of other elements and the diamond's growth history. Boron causes most blues; nitrogen causes most yellows; pinks and reds are linked to distortion of the crystal lattice, which is still being studied; and natural radiation causes most greens. Learn more in The Science of Diamond Color.

Have a question we haven't answered? Schedule a private consultation or contact us.