You have found the diamond shape, settled on a setting and decided you want a white metal. Then the jeweller puts two almost identical rings on the tray. One is white gold, the other platinum. From a photograph, you might struggle to tell them apart.

The difference becomes more interesting once you think about wearing the ring. How much weight do you like on your hand? Does a softly worn finish appeal, or would you want to restore that freshly polished shine? Those answers are more useful than choosing whichever metal sounds grander.

White gold is gold mixed with other metals to give it a paler colour. It is often finished with rhodium, a bright white coating. Platinum is naturally white and does not rely on rhodium plating to give it a white appearance.

Compare the lab created diamonds UK jewellers offer in the same ring design before deciding on a metal. Lily Arkwright’s Grace round solitaire, for example, comes in 18ct white gold and 950 platinum. For an in-person comparison at the jeweller’s Marylebone showroom, check which samples are available before booking.

The numbers refer to precious-metal content: 18ct gold is 75% gold, while 950 platinum is 95% platinum. They are not competing scores for how good a ring is. The Goldsmiths’ Company Assay Office explains how fineness marks identify metal content; the number is one part of the hallmark.

To check your colour preference, compare yellow gold lab-grown diamond rings with the same designs in white gold or platinum, ideally beside the jewellery you wear most.

A rhodium-plated white-gold ring can gradually look warmer as its surface coating wears and the underlying alloy becomes visible.

The National Association of Jewellers explains that rhodium replating intervals depend on wear and the thickness of the coating. Replating can restore the bright white appearance; ordinary cleaning does not replace that layer.

Before buying, ask whether the ring is plated, what replating currently costs and how the jeweller decides when it needs doing. There is no universal annual schedule. If maintaining a crisp, reflective finish matters to you, include that upkeep in the decision.

Platinum can scratch. With wear, its surface may develop the softer, less mirror-like finish known as patina. It can remain white while looking different from the day you bought it.

Platinum Guild International describes this satiny surface finish and explains that professional polishing can restore a brighter shine. Whether you want to do that is partly a matter of taste.

Ask to see a worn platinum sample if one is available. Comparing it with a freshly polished ring will give you a better idea of whether you like the softer finish.

Platinum is denser than gold alloys, so comparable rings of the same dimensions generally feel heavier in platinum. That extra weight can be pleasingly substantial or simply more noticeable than you want.

Try both on the intended finger and make sure their sizes and band dimensions are similar. Comparing a broad platinum ring with a fine white-gold band tells you as much about the designs as the metals. Give yourself a few minutes wearing each, rather than judging only by lifting them from the tray.

If you plan to add a wedding band, try the combination too. You are choosing the feel of the rings you expect to wear, not just the single ring in front of you.

Request prices for the same design with equivalent diamond specifications and the same ring size. Keep an eye on which options are selected: a different centre stone can make a metal comparison meaningless.

Then ask what the aftercare includes. Cleaning, inspecting the setting, polishing and replating are different jobs. A complimentary clean does not automatically mean every future service is included.

Find out how long the ring would usually be away for each service and whether it needs returning to the original retailer. The cost matters, but so does the practicality of arranging maintenance around work and everything else in the diary.

If you prefer a lighter feel and are happy to arrange replating when the finish needs it, white gold may suit you well. If you like a weightier ring and platinum’s natural colour, consider whether you also enjoy its patina or would want occasional professional polishing.

Neither choice requires you to predict decades of wear. Before ordering, ask to see the finish, feel the weight and understand the care. The right ring should appeal when you picture an ordinary Tuesday, as well as the moment it first goes on your finger.