Karat vs Carat: Gold Purity vs Diamond Weight

In this guide

    By Clint Casmiro, Co-Founder, Smiro Studio · Updated October 22, 2026

    Short answer: Karat (K) is gold purity: 14K is 58% gold and 18K is 75%. Carat (ct) is a diamond's weight, and one carat is 0.2 grams. On a ring they change different things: karat changes the metal's colour and hardness, carat changes the stone's size and price. On our orders the median centre stone is 3.0 carats, and 54% of rings are 14K yellow gold.

    3D render of a round six petal tulip solitaire engagement ring in yellow gold

    What is the difference?

    Karat (K) Carat (ct)
    Measures How much of the metal is pure gold How much a gemstone weighs
    Applies to Gold Diamonds and gemstones
    On our rings 14K (58% gold) or 18K (75% gold) Median centre stone 3.0 ct
    Price effect on our list 18K adds $400 CAD to our oval solitaire setting 2 ct to 3 ct adds $700 CAD on every listed ring

    From our listings and the SMIRO Ring Report, October 2026.

    What does 14K or 18K mean?

    The share of pure gold, out of 24 parts. 14K is 58% gold and 18K is 75%; the rest is other metals that make it harder. We usually recommend 14K: a softer colour, more durable, and it scratches less. 22K or 24K is possible on special request, and we do not recommend it for everyday wear. Platinum is 95% platinum. All of it in 14K vs 18K gold vs platinum.

    What does carat mean?

    Weight, not size. One carat is 0.2 grams. Two stones of the same carat can look quite different, because the shape and the length to width ratio decide how big a stone reads. See carat vs ratio.

    Which do most people choose?

    On 641 of our ring orders, 54% were 14K yellow gold and 76% were yellow gold of any karat. On 611 orders with the stone recorded, the median centre stone was 3.0 carats and 81% were between 2 and 4 carats. Everything is in the SMIRO Ring Report 2026.

    Why are they spelled differently?

    To keep them apart. In North America, karat with a K is gold and carat with a C is gemstone weight. In some other countries carat is used for both.

    Not sure which karat or carat suits you?

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    From our collection

    Toi et Moi Unique engagement ring in yellow gold, angled side viewToi et Moi UniqueCushion Low Profile Hidden Halo engagement ring in yellow gold, back angleCushion Low Profile Hidden Halo

    Questions we get about this

    What is the difference between karat and carat?

    Karat measures gold purity; carat measures a gemstone's weight.

    What does 14K gold mean?

    14 parts out of 24 are pure gold, which is 58%. 18K is 75% gold.

    How much does one carat weigh?

    0.2 grams.

    Is 14K or 18K better for an engagement ring?

    For everyday wear we usually recommend 14K: more durable and it scratches less. 18K has a richer colour.

    Keep reading

    Written by Clint Casmiro, co-founder of Smiro Studio with Karina. We are second generation jewellers. Our dad Kenny has more than 40 years at the bench and oversees production, and we have built over a thousand tulip basket rings. Every ring is designed in CAD and you approve 3D renderings before production. We ship free and insured across Canada and the US.

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