Lab-Grown Diamond Engagement Rings: A Plain-English Guide

When I bought my first engagement ring, nobody explained anything. I just nodded at words I didn't understand and hoped I wasn't overpaying. So here's the plain version of what a lab-grown diamond is, what it isn't, and what to ask before you buy one, from us or anyone else.

What a lab-grown diamond actually is

A lab-grown diamond is a real diamond. It's made of carbon arranged in the same crystal structure as a mined diamond, so it has the same hardness, the same way of bending light, and the same sparkle. The only difference is where it formed: in a machine over a few weeks, instead of deep in the earth over a very long time.

It is not a simulant. Cubic zirconia and moissanite are different materials that only look like diamond. A lab-grown diamond is diamond.

How they're made

There are two main methods:

• CVD (chemical vapor deposition): a thin diamond "seed" sits in a sealed chamber filled with a carbon-rich gas. The gas is heated until carbon atoms settle onto the seed and the crystal grows, layer by layer.
• HPHT (high pressure, high temperature): carbon is squeezed under enormous pressure and heat, much like the conditions deep underground, until it crystallizes into diamond.

After growing, many stones are treated to improve their color. That's normal, and a reputable seller will tell you if a stone has been treated. Then the rough crystal is cut and polished exactly the way a mined diamond would be.

Are lab diamonds flawless?

No, and anyone who tells you they all are is selling, not explaining. Lab-grown diamonds can have inclusions (tiny internal marks) and slight color tints, just like mined ones. They're graded on the same scales: cut, color, clarity and carat. A lab diamond can be anywhere from beautifully clean to visibly included.

So judge the stone in front of you, not the category. Ask for its color and clarity grades, and look at it in person or on video in good light. If a stone comes with a grading report, read it. It'll say clearly that the diamond is laboratory-grown.

Can you tell the difference?

Not by eye. A jeweler with a loupe usually can't either. Gem labs use specialized instruments to confirm whether a diamond was grown or mined. Day to day, on a hand, they look and wear the same.

Durability

Same as a mined diamond. Lab-grown diamonds are just as hard, so they're made for a ring you'll wear every day. Like any diamond, a hard knock at the wrong angle can still chip one. That's why the setting matters as much as the stone.

Price, and the honest trade-off

This is the big reason people choose lab-grown. For the same size and quality, a lab diamond usually costs a fraction of what a mined one does, and prices have kept falling. That means a bigger or cleaner stone for the same budget.

The trade-off: because new lab diamonds keep getting cheaper, they don't hold resale value the way mined diamonds historically have. If you're buying a ring to wear and love, that rarely matters. If resale value is important to you, it's worth knowing up front.

What about the environment?

Lab-grown diamonds don't involve digging a mine, but growing them takes a lot of electricity. How "green" a particular stone is depends mostly on where that power comes from, and that varies by grower. Be wary of blanket claims either way. If it matters to you, ask the seller what they know about where their stones are grown.

Questions to ask before you buy

• Is this diamond lab-grown or mined? (It should be stated plainly, in writing.)
• What are its cut, color and clarity grades?
• Has it been treated after growing?
• What's the total price, and what does it include?
• What does the warranty cover, and for how long?

How we do it

We're a family of jewelers in San Francisco. We make our rings ourselves, with no middlemen and no markup games. We'll tell you exactly what you're getting before you pay a cent. Every ring comes with our 2-year craftsmanship warranty.

If you'd like to see finished rings you can reserve today, start with the Classic Collection. If you have something specific in mind, tell us about it and we'll design it with you. No pressure, and no jewelry degree needed.