Why the 4Cs still apply
Lab-grown diamonds are diamonds. They are carbon, they crystallize in the same structure, and they are graded by the same laboratories using the same scales as mined stones. A report on a lab-grown diamond lists cut, color, clarity, and carat in the usual way, with the growth method noted alongside.
That means the buying logic does not change. The grades still describe how the stone handles light and how clean it looks. What changes is the price attached to each grade, because supply of lab-grown stones at high color and clarity is far larger than in mined goods.
Cut is the grade you actually see
Cut covers proportions, symmetry, and polish. It is the only one of the four that a cutter controls, and it decides how much light returns to the eye rather than leaking out the side or the bottom. A round brilliant graded excellent will look brighter than a stone of the same color and clarity graded good.
Cut grades are reported for round brilliants on most reports. Fancy shapes such as oval, emerald, and pear are usually given polish and symmetry grades rather than one overall cut grade, so proportion has to be judged from the stone or from video.
For a custom piece we can film the actual stone under controlled light before it ships. That is the closest substitute for holding it.
Color runs from D to Z
D is colorless, and the scale descends through E and F, near-colorless, into G to J, then K and below, where a warm tint becomes visible. On a lab-grown diamond, D to F costs more than G to J, and the difference is invisible once the stone is set in yellow gold.
Set in white metal, a warmer stone shows more. A J color stone in a white gold solitaire will read slightly creamy against the metal. The same stone in a yellow gold bezel reads white, because the surrounding metal carries the warmth.
Clarity runs from FL to I3
Clarity describes internal inclusions and surface blemishes. FL means flawless, IF means internally flawless, and VVS, VS, SI, and I follow in descending order. Inclusions graded VS2 and above are not visible to the unaided eye in a well-cut stone.
For most buyers, SI1 is where the practical line sits: clean to the eye, priced well below VS. Below that, inclusions start to show, and some can affect how light moves through the stone.
Inclusion placement matters as much as the grade. A small feather under the table is more visible than a larger one near the girdle, hidden by a prong.
Carat is weight, not width
One carat equals 0.2 grams. Carat weight does not translate directly into visible size, because a deep stone carries weight below the girdle where nobody sees it. A well-proportioned 0.9 carat can face up the same as a deep 1.0 carat.
Price per carat rises sharply at round numbers. A 0.95 carat stone often costs noticeably less than a 1.00 carat stone of the same grades, and no one can see the difference once it is set.
| Grade | What it means | Where the money goes |
|---|---|---|
| Cut: excellent | Light returns to the eye across the whole stone | Worth paying for at any size |
| Cut: good | Some light leaks through the pavilion | Acceptable in small side stones |
| Color: D to F | No tint visible in any metal | Pay for this in white metal |
| Color: G to J | Slight warmth, hidden by yellow gold | Best value in yellow settings |
| Clarity: VS and up | Clean under a loupe | Useful above one carat |
| Clarity: SI1 | Clean to the eye | Best value at most sizes |
| Carat: 0.90 to 0.99 | Faces up like a full carat | Avoids the round-number premium |
How the four grades interact
Grades are not independent. A stone with an excellent cut hides color and inclusions better than a poorly cut one, because the extra brilliance masks what sits behind the facets. That is why a well-cut H color SI1 stone can look better than a poorly cut F color VS2 stone of the same size.
Spending order for most rings: cut first, then color to match the metal, then clarity to the point where the stone is eye clean, then carat with whatever remains. Buyers who reverse that order usually end up with a large stone that looks flat.
What to check on the report
- Confirm the report number matches the laser inscription on the girdle.
- Check that the growth method is stated, CVD or HPHT.
- Read the measurements in millimeters alongside the carat weight.
- Look at the inclusion plot for anything under the table.
- Confirm the report came from the lab named on it, not a reseller's summary.
We send the certificate with the stone and match the inscription before packing. If you are weighing a lab-grown stone against moissanite, the learn section covers the optical differences, and the loose stones page lists what is currently available. For a full ring build, the custom process explains where stone selection falls in the timeline.