3ct Trilogy Lab-Grown Diamond Engagement Ring – Round Brilliant Cut
The Karat Store · Handcrafted in Solid Gold
A 3ct round brilliant-cut lab-grown diamond takes centre stage in the 3ct Trilogy Lab-Grown Diamond Engagement Ring, crafted in solid 10ct, 14ct or 18ct gold. The diamonds are graded F colour, VS2 clarity, for a bright, clean sparkle. The round brilliant cut returns more light than any other shape, so it gives the most sparkle from every angle. The trilogy design uses three stones, often said to stand for your past, present and future. It is one of Britain's best-loved engagement ring styles.
It is a proposal ring made to be worn every day for a lifetime, and it pairs beautifully with a matching wedding ring. Available in yellow, white or rose gold and UK ring sizes D to Z+1.
Complementing the centre diamond are additional lab-grown diamonds in a mix of round and trapezoid shapes, with a combined carat weight of 1.48. These side stones enhance the design’s symmetry and brilliance, creating a sophisticated trilogy arrangement that embodies balance and harmony. Crafted from solid gold, the band is elegantly proportioned, measuring 2 mm in width and 1.8 mm in height, offering durability and comfort while maintaining its refined aesthetic. The absence of rhodium plating highlights the natural warmth and richness of the gold, adding a timeless charm to this exquisite piece.
Yes. A lab-grown diamond has the same chemical, physical and optical properties as a mined diamond. It is simply grown in a controlled environment rather than mined. It will pass a diamond tester and is just as hard (10 on the Mohs scale).
The round brilliant cut returns more light than any other shape, so it gives the most sparkle from every angle.
The trilogy design uses three stones, often said to stand for your past, present and future. It is one of Britain's best-loved engagement ring styles.
18ct gold (75% pure gold) has the richest colour and a luxurious weight. 14ct gold (58.5% pure gold) is the most popular balance of colour, durability and value. 10ct gold (41.7% pure gold) is the hardest-wearing and most affordable option. Every option is solid gold all the way through, not plated.
White gold is finished with a bright rhodium plating. Over time, usually every 12 to 18 months with daily wear, it can soften to a warmer tone. Any jeweller can re-plate it quickly to restore the bright white finish.
This ring is made to order in UK sizes D to Z+1, so it is crafted to your size from the start. It can usually be resized later by a jeweller by one or two sizes. If you are unsure of your size, a local jeweller can measure you for free, or see our ring size guide.
Depending on how low the setting sits, a straight band may leave a small gap. A curved or contoured wedding ring will sit flush. Message us and we will suggest a matching band.
Explore more: Engagement Rings · Round Engagement Rings · Trilogy Engagement Rings · Lab-Grown Diamond Engagement Rings
Every piece is cast and finished by hand in genuine solid gold — choose 10ct, 14ct or 18ct in yellow, white or rose gold. Never plated, never filled, made to be worn for a lifetime.
Stones are conflict-free: lab-grown diamonds, moissanite and hand-selected natural gemstones, each set and polished by our artisans.
Your jewellery is crafted to order in your chosen gold colour, carat and size.
All ring sizes are shown in UK sizes (letters), and every size is the same price within each gold colour and carat. Half sizes (e.g. L½) are available in the size selector.
| UK | Inside diameter (mm) | Inside circumference (mm) |
|---|---|---|
| H | 14.7 | 46.1 |
| I | 15.1 | 47.4 |
| J | 15.5 | 48.7 |
| K | 15.9 | 49.9 |
| L | 16.3 | 51.2 |
| M | 16.7 | 52.5 |
| N | 17.1 | 53.8 |
| O | 17.5 | 55.0 |
| P | 17.9 | 56.3 |
| Q | 18.3 | 57.6 |
| R | 18.7 | 58.9 |
| S | 19.1 | 60.2 |
| T | 19.6 | 61.4 |
| U | 20.0 | 62.7 |
| V | 20.4 | 64.0 |
| W | 20.8 | 65.3 |
| X | 21.2 | 66.5 |
| Y | 21.6 | 67.8 |
| Z | 22.0 | 69.1 |
| Z+1 | 22.4 | 70.4 |
Not sure of your size? Measure the inside of a ring that already fits, use a ring sizer, or visit a local jeweller for a professional sizing. We are happy to help — get in touch before you order.
Remove your jewellery before swimming, cleaning or the gym. Clean gently with warm water, mild soap and a soft brush, then dry with a lint-free cloth. Store each piece separately to prevent scratches.
Solid Gold, Always
Crafted in genuine 10ct, 14ct or 18ct gold — never plated, never filled.
Made to Order
Handcrafted for you and dispatched within 4 working days.
Conflict-Free Stones
Lab-grown diamonds, moissanite and hand-selected gemstones.
Personal Guidance
Questions on ring size, gold or stones? We are here to help.
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