Why the 4Cs work a little differently for lab diamonds
The 4Cs are cut, color, clarity and carat. They were created to describe mined diamonds, and lab grown diamonds are graded on exactly the same scales. A G color is a G color whatever the origin.
What changes is the money. Because lab diamonds cost much less, the price gaps between grades are smaller. That means you can often afford a higher grade than you expected. It also means it is easy to overspend on grades you will never see. The trick is to spend where your eyes notice and save where they do not.
Here is how we suggest thinking about each C, in order of importance.
Cut: spend here first
Cut is how well a diamond is shaped and finished: its proportions, angles, polish and symmetry. It decides how much light comes back to your eye. A well cut diamond looks bright and lively. A poorly cut one looks dark, glassy or flat, even if its color and clarity grades are high.
For round brilliants, reports give a cut grade. Aim for Excellent, or Ideal where that grade is used. For fancy shapes such as oval, pear or emerald there is usually no single cut grade, so polish and symmetry help, and your own eyes matter most. Look for an even outline and bright light across the face.
Many lab diamonds are cut very well, but not all. Cut is the one grade we tell people not to trade away. You can see it from across a room.
Color: the easiest place to save
Color is graded on a scale from D, completely colorless, down to Z, which has a noticeable yellow or brown tint. Most lab diamonds sold for jewelry fall in the D to H range.
| Grade | What you see face up | Good fit for |
|---|---|---|
| D to F | Icy, colorless | Platinum or white gold, step cuts like emerald |
| G to H | Looks white in most light | Most settings, the value sweet spot |
| I to J | A faint warmth, mostly from the side | Yellow or rose gold, which warms the stone anyway |
Face up and set in a ring, most people cannot tell D from G without a stone beside it for comparison. Brilliant shapes like round, oval and radiant hide color well. Step cuts like emerald show more, so go a little higher there. Metal matters too. Yellow gold makes a near colorless stone look white against it.
Clarity: aim for eye clean
Clarity describes tiny internal features, called inclusions, and surface marks, called blemishes. The scale runs from Flawless through VVS, VS and SI down to Included. Grades are judged under 10x magnification, not by eye.
Lab diamonds can have inclusions too. Depending on how the stone was grown, they may look like small dark crystals, fine lines or faint clouds. A good goal for most buyers is eye clean: no inclusion visible at normal viewing distance.
- VVS1 and VVS2. Inclusions are very hard to find even under a loupe. Beautiful, but you are paying for something nobody can see.
- VS1 and VS2. Usually eye clean. A practical and popular choice.
- SI1. Often eye clean in brilliant shapes, worth checking stone by stone.
Step cuts like emerald and asscher have big open facets that show inclusions more, so VS or better is safer there. Our shapes guide covers which shapes are forgiving.
Carat: weight, not size
Carat is weight. One carat equals 0.20 grams. Carat does not directly tell you how big a stone looks face up. Two diamonds of the same weight can spread differently. An oval or marquise often looks bigger than a round of the same weight, because more of the weight sits in the visible face.
Prices tend to step up at round numbers like 1, 1.5, 2 and 3 carats. A stone just under one of those marks, such as 0.95 or 1.90 carats, can cost less and look the same on the hand. Lab diamonds make larger sizes much more reachable. As a guide, a 1 carat round lab diamond starts from about $640, and the price depends on the other three Cs. See our lab diamond price guide for more on how size and grades affect cost.
Putting the four together
There is no single right combination. It depends on your budget and on what you notice. A sensible starting brief for many people looks like this:
- Cut: Excellent or Ideal for rounds, bright and even for fancy shapes.
- Color: G or H, or higher for emerald cuts and platinum settings.
- Clarity: VS2 or better, or SI1 if you can confirm it is eye clean.
- Carat: whatever size looks right on the hand, often just under a round number.
From there, move one grade at a time and compare. If you cannot see the difference, keep the money. If you can, decide whether it is worth it to you.
Beyond the 4Cs
A few other details show up on reports and are worth a glance.
- Polish and symmetry. Good to Excellent is fine. They support the cut grade.
- Fluorescence. A glow under ultraviolet light. It rarely affects how a stone looks in normal light.
- Measurements and ratio. For elongated shapes, length divided by width tells you how slim or chunky the stone will look.
Our guide to IGI vs GIA reports walks through every line of a report.
Test your brief in person
The best way to settle the 4Cs is to look at them. Send us your brief with the loose diamond request. We pull three to five stones that fit, including one a grade above and one a grade below where it helps, so you can see where the differences start.
Then book a viewing at 30 West 47th St, Suite 805, or call (732) 581-7932. If you are choosing for an engagement ring, browse our round lab grown engagement rings and other settings first and save the ones you like.
