How To Choose Your Perfect Moissanite Or Lab Diamond Stone Size

The Stone Lab 6 Claws Shoulder Set Round Lab Diamond Engagement Ring on hand with Almond White Background

One of The Stone Lab’s most frequently asked questions is "What stone size should I choose?". Unfortunately, there is no right answer to this question. Stone size is entirely a matter of personal choice which is completely individual to the wearer. As a guide, typically 1.0ct and 1.5ct are the most popular sizes for a brilliant round cut moissanite engagement ring. However, popularity doesn't mean that this size is right for you. To help you on your path to choosing your perfect stone size, we've collated all the necessary information and points to consider when selecting your centre stone.

Carat Weight

Carats are the universal unit of measurement for precious gemstones. Unlike the name may suggest, carat size actually refers to the weight of a gemstone, where 1ct is equivalent to 200 milligrams. The larger the carat, the heavier the stone will be, which does not necessarily mean an increase in stone size. Two gemstones can be equivalent in weight but not size, therefore, carat weight is not a true indicator of stone size. For example, moissanite weighs roughly 15-18% less than diamonds, meaning that a brilliant round 6.5mm diamond weighs approximately 1ct compared to moissanite which weighs 0.88ct. Therefore, to make comparison easier for our customers we list our moissanite stones with approximate weights which are equivalent to diamond, according to their diameter.


To accurately understand the size of a gemstone, it is important to look at its measurements in millimetres. All carat weights listed on our website are noted in comparable millimetre (mm) size to scale, approximate average carat weights and approximate diamond equivalent weights. For further View our stone size comparison chart for more information.


What's Your Budget?

A strong appeal of moissanite engagement rings is the fact that they enable couples to opt for a larger centre stone for a fraction what a natural diamond would cost them. This presents the perfect opportunity for couples dreaming of a sizeable centre stone to be able to afford their dream ring - a fact which is highlighted on the Boho Weddings website. However, your budget may determine the stone size you choose, due to the relationship between the cost and size of moissanite gemstones. For those wishing to portray their moissanite centre stone as a natural diamond, you may also want to consider how realistic it would be for you to afford your chosen carat size in a diamond equivalent. Although a 2.2ct moissanite centre stone fall within your budget, a 2.2ct diamond can cost up to £50,000. Nevertheless, if you aspire to own an extravagant gemstone engagement ring, don't let this put you off. Here at The Stone Lab, we believe Moissanite is a stunning stone superior to mined diamonds in many ways, with more brilliance, fire and sparkle, as well as strong ethical origins, which everyone should be proud to show off!

What's Your Style?

If you’re planning a surprise engagement for your partner and are unsure of what stone size to choose, we recommend that you consider their personal style. Consider which jewellery your loved one owns and wears, as well as their fashion tastes and opt for a stone to compliment this. If your fiancé-to-be is a minimalist, a smaller stone size may be more desirable, whereas for those with a love for glamour and extravagance, a larger centre stone will be more appealing. Make sure to check out our moissanite earrings and pendants for a beautiful bridal set.

Large stones

To answer this you must consider the lifestyle of the wearer. A larger stone needs to be worn with care, as it poses a higher risk of being knocked and damaged due to its size. Therefore, if the owner has a physical job or lives a very active lifestyle it may be advised to choose a smaller centre stone (or ensure that you invest in insurance for your ring!)

You may also want to consider the heavy weight of larger stone sizes. If you or your partner aren’t used to wearing a lot of jewellery this heavier carat weight may be uncomfortable to wear. However, if you are dreaming of a large stone size, don’t let this put you off buying your dream ring; we’re sure you will easily be able to adjust to wearing a ring you truly adore!

Stone Cuts & Setting

Certain cuts, settings and metals can create the illusion of a larger centre stone. The intense sparkle from brilliant round moissanite of a Charles & Colvard Forever One creates the appearance of a larger stone, compared to equivalent carat weights in alternative cuts. A bright white metal band, such as platinum or 18k white gold, can enhance this sparkle by reflecting light through the centre stone for maximum brilliance and shine - producing the effect of a larger centre stone.

Elongated cuts such as oval, pear and marquise are also preferred cuts for those lusting after a large centre stone. Not only do these cuts appear bigger due to their shape, but they also elongate the wearers hand, subsequently creating a slender appearance which accentuates the size of the centre stone. The setting you choose can make your chosen gemstone more prominent. For creating the illusion of a larger stone, a halo setting is superior, where the surface area if the stone is maximised, and is surrounded by a halo of sparkling G/H SI conflict-free diamonds. Compliment this setting with a knife edged or petite band and slender prongs to exaggerate the centre stone’s size.

How Big is Too Big?

This is another question with no right answer. No stone is too big if it's what yourself or your partner dreams of. However, if you are unsure of the ideal stone size for your ring, keep in mind the wearers hand. A big stone can appear even larger on a small hand and vice versa. However, this is dependent on the appearance desired by the wearer - there is no right or wrong when it comes to how the ring appears on the hand.

Here at The Stone Lab, we offer free hand comparisons so you can compare your dream moissanite engagement ring in a number of different sizes using our to-scale hand mock-up service. This allows our customers to truly envisage the appearance of the stone on your own or your partner’s hand. If you are interested, please get in touch with us via email. 

Ultimately, an engagement ring is a symbol of love. As the popular saying goes: ‘you can’t put a price on love’ - this should be embodied when shopping for an engagement ring. The story behind an engagement ring is a symbolism of the love shared between you and your partner and not to flaunt huge stones and expensive purchases. The size of your centre stone doesn’t reflect the amount of love your partner has for you. No matter how big or small your chosen gemstone, the love within your relationship doesn’t change. It’s your ring to be worn every day for a lifetime and, as long as yourself and your partner are happy, no stone size is too big or small.