Colour is the part of moissanite buying that generates the most refund requests. Not because the stones are bad, but because shoppers read "D" on a listing and assume they are buying a diamond-grade colour. Moissanite is not graded on the GIA diamond scale at all, and the letters you see are closer to a house convention than a laboratory measurement.

Where moissanite colour comes from

Moissanite is silicon carbide, grown from a seed crystal in a furnace. The as-grown crystal is not colourless. Makers add trace elements to push it towards white, and the process is judged in much the same way a diamond cutter judges rough: how much carat weight am I willing to lose in exchange for whiter material?

That trade-off explains everything about moissanite pricing. A near-colourless stone of a given size costs the grower a larger piece of rough than an F-grade one. The tint itself is usually a faint yellow, grey or green cast, and it is muted rather than obvious.

What D, E and F actually mean here

On a diamond report, D, E and F are tightly defined colourless grades verified stone by stone against master stones. On moissanite, those letters describe a broad band of material. Sellers use them because buyers recognise them, and because "colourless" alone has been stretched so far that it has stopped meaning anything.

A useful way to hold it in your head:

  • D–E — the whitest moissanite a grower will release. Essentially no body colour face-up, though the material is never as dead-white as a true D diamond.
  • F — the workhorse grade. Face-up white in a well-cut stone at 1ct, and the grade most reputable sellers ship.
  • G, H, I and "near-colourless" — a visible warmth, most often yellow, that shows in the body of the stone rather than in the sparkle.
  • Unlabelled or "premium white" — a marketing term with no fixed meaning. Ask for a named grade or walk away.

Where you will actually see a tint

Four places, in this order of likelihood.

Against a white background, face-down. This is the least forgiving view and the one most jewellers use. A stone that looks white on a hand can look distinctly creamy on a white paper tray.

From the side, through the crown. Fancy shapes with a wide table show body colour sideways more readily than a round brilliant, because a round's pavilion bounces light back through the middle. Emeralds and radiants with step or wide facets are the most exposing.

At 2ct and above. Colour reads as a function of depth. Two carats of the same material as a 1ct stone will look warmer, every time. If you are ordering a large stone and colour matters to you, buy the top grade rather than the middle one.

Under warm indoor light. Filament and halogen bulbs push yellow tones forward. Stones that look icy in a north-facing window can look slightly buttery in a hotel lobby, and most proposals happen indoors in the evening.

Why double refraction changes what you see

Moissanite has a refractive index of 2.65 against diamond's 2.42, and it is doubly refractive, which diamond is not. In practice the higher index is why a moissanite reads bright in dim light where a diamond goes quiet. The double refraction is why, under a loupe, you can see doubled facet edges at the back of the stone. That is a property, not a flaw. It has nothing to do with the colour grade, but it does sharpen the contrast at facet junctions, which makes any warmth in the body colour a touch easier to spot when you inspect closely.

How to judge colour before you buy

Skip the letters and ask for two things: photographs of the actual stone on a white background, and the millimetre dimensions from the certificate. A retailer who will not send a plain white-background photo is telling you something.

If you are buying in person, take the stone to a window. Daylight, ideally overcast, is honest light. Shop lighting is not, and almost every moissanite looks white under a display spotlight.

One more thing worth knowing. The price gap between D and near-colourless moissanite is small — often €30 to €80 on a ring — because the rough cost difference is small. If a seller is charging €200 extra for "D colour", the premium is marketing, not material. The exception is very large stones, where good rough genuinely costs more.