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Moissanite vs Lab Grown Diamond Cost: The Real Gap

Moissanite vs lab grown diamond cost, in CAD: what each stone runs by size, why the gap narrowed, and when the cheaper stone is genuinely the right call.

Moissanite is still the cheaper stone, but at the sizes most people actually buy, the saving is a few hundred dollars on a ring that costs a few thousand. In our own loose-stone pricing as of August 2026, a 6.5 mm round moissanite runs roughly $250 to $600 CAD, while a well-cut lab-grown diamond of the same diameter in G colour and VS2 clarity runs roughly $650 to $1,400. The gap only becomes a real financial argument above about 2.5 carats, and that is the honest version of this comparison.

What each stone costs by size

Moissanite is sold by millimetre diameter, not carat weight, and there is a physical reason for that. The Handbook of Mineralogy records moissanite (silicon carbide, SiC) with a measured density of 3.1 to 3.29, while the US Federal Trade Commission's own definition of diamond in 16 CFR 23.12 gives a specific gravity of approximately 3.52. A moissanite cut to the same diameter as a one-carat diamond therefore weighs less than a carat. When a seller advertises a "1 carat moissanite," they almost always mean diamond-equivalent size at 6.5 mm.

Here is what we see in our own inventory as of August 2026, comparing round brilliants at matched diameters. Lab-grown prices assume G colour, VS2 clarity and a top cut grade.

DiameterDiamond equivalentMoissanite (CAD)Lab-grown diamond (CAD)Difference
6.5 mm~1.00 ct$250 โ€“ $600$650 โ€“ $1,400~$400 โ€“ $800
7.3 mm~1.50 ct$350 โ€“ $800$950 โ€“ $2,200~$600 โ€“ $1,400
8.1 mm~2.00 ct$450 โ€“ $1,000$1,400 โ€“ $3,200~$950 โ€“ $2,200
9.3 mm~3.00 ct$650 โ€“ $1,400$2,600 โ€“ $6,500~$1,900 โ€“ $5,100

These are our ranges on our own shelf, not an industry index, and they move. Read them as a shape, not a quote. Current pricing lives in the loose diamond search.

Why the saving matters less than people expect

The stone is not the whole ring. A finished ring is a stone plus a setting plus metal weight plus labour, and the setting does not get cheaper because you chose the cheaper stone. Our settings in 14k and 18k gold generally sit between about $900 and $2,500 as of August 2026, with platinum higher because the metal is denser and harder to work.

Run the arithmetic on a one-carat-look solitaire:

  • Moissanite in a $1,400 setting: roughly $1,700 to $2,000 all in
  • Lab-grown diamond in the same setting: roughly $2,100 to $2,800 all in

That is a difference of a few hundred dollars on a two-thousand-dollar purchase. It is real money, but it is not the order-of-magnitude saving the comparison is usually sold as. Where moissanite genuinely changes the maths is at three carats and above, where skipping the diamond can save four thousand dollars or more and put a much larger stone within reach.

They are not the same material, and the rules say so

This is where the price difference comes from. A lab-grown diamond is diamond. Under 16 CFR 23.12, a diamond is "a mineral consisting essentially of pure carbon crystallized in the isometric system," and a laboratory-grown stone qualifies provided the seller makes "a clear and conspicuous disclosure" using wording such as "laboratory-created" or "laboratory-grown" that conveys "that the product is not a mined stone."

Moissanite does not meet that definition at all. It is silicon carbide, a different mineral. The FTC guides treat that class of stone separately: 16 CFR 23.25 requires that a "laboratory-grown, laboratory-created, synthetic, imitation, or simulated stone" be described with qualifying language of "equal conspicuousness," and notes that a word like "faux" on its own does not do the job. 16 CFR 23.27 goes further, calling it unfair or deceptive to use "real," "genuine," "natural," "precious" or similar terms for a product that is manufactured artificially.

Those are US rules and they do not bind a Canadian retailer directly, but they are the clearest published statement of the nomenclature the trade follows on both sides of the border. Canada's own marking law, set out in the Competition Bureau's Guide to the Precious Metals Marking Act and Regulations (last updated 17 March 2025), governs the metal rather than the stone: marking is not mandatory, but if a quality mark is applied it must be truthful and accompanied by a registered Canadian trade mark.

What you can actually see

Two differences are visible, and one of them is subtle enough that most people never notice it.

The mineralogy entry lists moissanite as uniaxial with refractive indices of ฯ‰ = 2.654 and ฮต = 2.697, meaning light splits into two rays as it passes through. Diamond has a single refractive index of 2.42 per the FTC definition. That doubling shows up as blurred or paired facet edges when you look into a moissanite through a loupe, and it is more obvious in larger stones and in step cuts like emerald. In a mounted 1-carat round, across a table, most people will not see it.

The other difference is fire. Moissanite throws noticeably more coloured flash under point lighting such as restaurant spots or car headlights. Some people love that. Some describe it as looking wrong. There is no objective answer here, and anyone who tells you moissanite is "indistinguishable" is overselling.

On durability, moissanite is hardness 9.5 on the Mohs scale against diamond's 10. Mohs is an ordinal scratch scale, not a linear one, and the interval between 9 and 10 is large. In practical terms both are hard enough for daily wear; neither is chip-proof, and a sharp knock on a corner or a thin girdle can damage either.

Paperwork, and what you are not buying

A lab-grown diamond of any real size comes with a lab report. HRD Antwerp, for example, states that where a stone is found to be laboratory grown it issues a Laboratory Grown Diamond Grading Report with "this clear wording on the cover," notes the laser inscription and reference number, and uses "the same nomenclature as in a Natural Diamond Grading Report, with a detailed description of the 4Cs." Its 4Cs guidance defines VS as "very small inclusions" and SI as "small inclusions," both assessed at 10x magnification, and grades cut across proportions, polish and symmetry as excellent, very good, good or fair.

Moissanite has no equivalent. Colour is described in vendor terms like "colourless" or "near colourless" that are not tied to a lab-issued scale, and clarity is rarely graded at all. That is not a scandal, it is just a different product, but it means you cannot compare two moissanites the way you can compare two certified diamonds. Part of what the diamond premium buys is a document that lets you shop on specifications rather than trust.

Neither stone has a resale market worth planning around. Treat both as a purchase, not an asset.

Why CAD quotes drift

Loose stones are traded upstream in US dollars, so Canadian prices move with the exchange rate even when nothing about the stone has changed. The Bank of Canada's daily average rate was 1.3839 Canadian dollars per US dollar on 25 August 2026. A quote you were given in spring is not a quote today, in either direction.

When moissanite is the right call

Plainly: more often than the diamond trade admits, and less often than moissanite sellers claim.

  1. You want 3 carats or more. This is the strongest case. The saving is thousands, not hundreds.
  2. The ring will take hard use. A travel ring, a job with gloves and tools, a stone you would rather not worry about.
  3. You are buying a second ring. An anniversary upgrade or a stacking band where the budget is genuinely fixed.
  4. You prefer the look. Some people want the extra fire. That is a legitimate reason, not a compromise.
  5. The alternative is going smaller than you want in a diamond. A 2.5 carat moissanite you like beats a 0.9 carat diamond you settled for.

If none of those apply and you are shopping around one carat, put the few hundred dollars into the diamond. Better still, spend it on cut grade rather than carat weight, which is where visible sparkle actually comes from.

What to do next

Start with the stone, because it sets the budget. Compare real prices at the diameter you want in the loose diamond search, then pick from the engagement ring settings and preview the pair in 3D before you commit. When you are settled, finish the ring with metal, size and engraving. If you are still deciding between shapes or metals first, the other guides cover those in more detail.

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