0.75 Carat Diamond Guide: Size in mm, Look on the Hand, Price and Grades

What is a 0.75 carat diamond?

A 0.75 carat diamond weighs three-quarters of a carat. One carat is exactly 0.2 grams, so a 0.75 carat stone weighs 0.15 grams, about the same as a few grains of rice. The trade divides each carat into 100 points, so you will also hear it called a 75-pointer or a three-quarter carat. Our guide to how carat weight is measured and recorded explains the scale in more detail.

Carat is a measure of weight, not size. Two diamonds that both weigh 0.75 carat can look quite different face-up (the view from above, as you see it in a ring) because of their shape and how deeply they are cut. That is why this page gives millimetre sizes for every shape, not just the weight. Carat is also only one of the four grading factors; colour, clarity and cut all change how a stone looks and what it costs, and our overview of the 4Cs of diamond grading shows how they fit together.

Grading reports give the weight to two decimal places, so a stone listed as 0.75 carat will say exactly that on its report. Be careful with jewellery labelled 3/4 ct TW: TW means total weight, the combined weight of every diamond in the piece, so a 3/4 ct TW cluster ring may have no single stone anywhere near 0.75 carat. If you meet a term here you do not recognise, our glossary of jewellery terms has a plain-English definition.

How big is a 0.75 carat diamond in mm?

A well-cut 0.75 carat round brilliant measures about 5.7–5.9 mm across, with 5.8 mm the most common figure. Fancy shapes spread the same weight differently. Elongated shapes such as ovals, pears and marquises put more of their weight into length, so they cover more of the finger. Step cuts such as emerald and Asscher cuts carry more weight below the girdle (the outer edge), so they look smaller for their weight.

These are typical figures only. Within the same shape, depth changes the face-up size. A round cut deep, at 64% or more of its width, might measure only 5.6 mm, while one cut shallow might spread to 6.0 mm but leak light and look glassy. Always check the measurements on the report rather than relying on the carat weight. For every shape at every weight, see our full millimetre to carat chart for all shapes, and compare with half carat diamond sizes to see how far the step up really is.

What does a 0.75 carat diamond look like on a finger?

On most hands, a 0.75 carat round covers roughly a third of the finger's width. That reads clearly as a substantial centre stone from across a table, without the height and bulk of larger diamonds. On a slimmer finger it looks bigger, because it covers more of the width; on a larger finger it looks more modest. The table below shows the approximate share of finger width each stone covers at common Australian ring sizes.

An oval, pear or marquise set north-south (pointing along the finger) adds length rather than width, which many people find makes the finger look longer and slimmer. A 7.0 mm oval is more than a millimetre longer than a 5.8 mm round of the same weight, and that extra length is easy to see on the hand.

The same weight works well in other jewellery too. A pair of 0.75 carat studs, 1.50 carat total, is a generous size for everyday earrings, and a 0.75 carat pendant sits clearly on the collarbone. If you want something quieter for studs or a stacking ring, our page on diamonds from 0.25 to 0.4 carat covers the smaller sizes.

0.75 vs 1 carat diamond: can you see the difference?

Going from 0.75 to 1 carat adds a third more weight, but the diameter of a round only grows by about 0.6 mm, from 5.8 to roughly 6.4 mm. Weight spreads through the whole depth of the stone, so face-up area grows more slowly than carat weight. A 0.75 carat round shows about 80% of the face-up area of a 1 carat round, for much less than 80% of the price in natural diamonds.

The reason natural prices nearly double between 0.75 and 1 carat is demand: the 1 carat mark is a round number many people aim for, and stones that reach it are priced in a higher bracket per carat. Lab-grown prices rise much more gently across the same range. Our 1 carat diamond guide covers that size in full, and if you are weighing a slightly bigger stone, see 1.25 carat stones and one and a half carat diamonds.

The same pattern runs right up the scale: each popular weight carries a price step, and the steps get larger as diamonds get rarer. Compare 2 carat sizes and prices, then three carat diamonds, 4 carat stones, five carat diamonds and very large 6 to 10 carat diamonds to see how sharply natural prices climb.

How much does a 0.75 carat diamond cost in Australia?

A natural 0.75 carat round with good everyday grades (G–H colour, VS2–SI1 clarity, Excellent cut) costs roughly AUD $3,200–$6,500. A lab-grown 0.75 carat round with similar grades is roughly AUD $450–$1,300. These are loose stone prices; the setting is extra. Prices move with the market, especially for lab-grown, so treat the table as a guide rather than a quote.

Fancy shapes usually cost less per carat than rounds of the same grades, because cutting a round wastes more of the rough crystal. A 0.75 carat oval or cushion with the same colour and clarity will typically sit below the round figures above.

Where the weight falls matters too. Diamond prices move in brackets, and the main ones around this size are 0.50–0.69, 0.70–0.89, 0.90–0.99 and 1.00 carat and up. A 0.75 carat sits in the 0.70–0.89 bracket, so a 0.72 and a 0.85 of the same grades cost about the same per carat. That gives you room: a 0.70–0.74 stone can look almost identical for less, while a 0.85–0.89 gives you more size before the jump at 0.90. The price per carat climbs in each higher bracket, which is why 2.5 carat diamonds cost so much more than double a 1.25. For lab-grown options above this size, see lab-grown diamond sizes from 1 to 5 carats.

Should you choose a natural or lab-grown 0.75 carat diamond?

Both are real diamond: crystallised carbon with a hardness of 10 on the Mohs scale and a refractive index of about 2.42. A natural diamond formed deep in the earth over a very long time and was mined. A lab-grown diamond (also called laboratory-grown) is grown in weeks using one of two methods: CVD (chemical vapour deposition, building the crystal layer by layer from carbon-rich gas) or HPHT (high pressure, high temperature, recreating the conditions that form natural diamond). They look identical to the eye and can only be told apart with specialist laboratory equipment.

• Disclosure: every lab-grown stone should come with a report from a lab such as IGI or GIA stating it is laboratory-grown, and most carry a tiny laser inscription on the girdle saying so.
• Price: lab-grown costs much less than natural at 0.75 carat, so many people who start at a 0.75 carat natural end up comparing it with a 1 to 1.5 carat lab-grown stone for a similar budget.
• Rarity: natural diamonds are finite and each formed under unique conditions; for some people that origin matters, for others it does not.
• Resale: neither type should be bought expecting to sell it later for what you paid. Lab-grown resale values are very low, and natural diamonds also resell well below retail.
• Treatments: some lab-grown diamonds have their colour improved after growth; the report will note this. Natural diamonds can be treated too, and that must also be disclosed.

What colour and clarity suit a 0.75 carat diamond?

At 0.75 carat, the stone is large enough that colour starts to show in a white metal setting, but small enough that SI1 inclusions (internal features) are often invisible without magnification. The aim is an eye-clean diamond, one with nothing you can see at normal viewing distance, and a colour that looks white in the metal you choose. Cut comes first: for rounds, choose an Excellent cut grade, which usually means a total depth of about 59–62.5% and a table (the large top facet) of about 54–58%.

• Fluorescence: faint to medium blue fluorescence (a glow under ultraviolet light) rarely affects appearance and can lower the price slightly; very strong fluorescence occasionally makes a stone look hazy, so view it first.
• Clarity position: an inclusion under the table is easier to see than one near the edge, where claws can hide it. Check the plotting diagram on the report.
• SI2: some SI2 stones are eye-clean at this size, but many are not; only consider one after seeing a clear, magnified video.

For more on how these grades interact, and why cut has the biggest effect on sparkle, see our guide to how cut, colour and clarity work together.

Which ring settings make a 0.75 carat diamond look bigger?

A 3/4 carat diamond ring can look larger or smaller than it is depending on the setting around it. These choices make the biggest difference:

• Four claws instead of six: fewer, finer claws cover less of the diamond, so more of the outline shows.
• A slim band: a band of about 1.8–2.2 mm makes a 5.8 mm stone look generous by contrast; a heavy 3 mm band makes it look smaller.
• Halo: a ring of small diamonds about 1.0–1.3 mm each around the centre takes the overall face-up size of a 0.75 carat round to roughly 8.5–9 mm.
• Bezel: a thin rim of metal around the edge is very secure; a fine white metal bezel can add to the apparent size, while a thick one can frame it tighter.
• Elongated shapes: a 0.75 carat oval diamond or pear set north-south covers more finger length than a round of the same weight.
• Metal colour: white gold or platinum claws blend with the diamond, so the stone reads as one larger white shape.

How do you choose a 0.75 carat diamond? Step by step

1. Decide natural or lab-grown. Set a budget and confirm on the report which type the diamond is.
2. Choose the shape. Use the millimetre table above; elongated shapes look larger for the weight, step cuts more compact.
3. Put cut first. For rounds, choose Excellent cut; for fancy shapes, check the ratio, depth and a 360° video for dark areas.
4. Match colour to the metal. G–H in white gold or platinum, I–J in yellow or rose gold.
5. Check clarity by eye. VS2–SI1 is usually eye-clean at this size; confirm with a magnified video and the plotting diagram.
6. Use the price bracket. Compare 0.70–0.74 and 0.80–0.89 stones alongside 0.75 to find the size and price balance you like.
7. Read the measurements. Compare millimetres, not just carats, so you know the true face-up size.
8. Plan the setting. Choose the claws, band width and any halo before you commit, so the stone and ring work together.