Side by side in a shop, freshly polished, white gold and platinum can be almost impossible to tell apart. That similarity stops at the surface. One is a near-pure precious metal that is white all the way through; the other is a yellow metal alloyed and, in most cases, plated to look white. The difference shows up over years of wear rather than on day one.
What each one actually is
Platinum jewellery is typically 950 — 95% pure platinum, alloyed with a small amount of another platinum-group metal, usually for workability rather than to change the colour. Platinum is naturally white, so nothing needs to be added to bleach it and nothing needs to be plated over it. What you see is the metal itself.
Gold is naturally yellow, and pure gold does not go white on its own. White gold is made by alloying gold with a metal that pulls the colour toward white — historically nickel, and increasingly palladium in better-quality pieces. Nickel-based white gold is the cheaper route and typically comes out slightly grey or with a faint yellow cast rather than a true bright white; palladium-based alloys get closer to white on their own but cost more and are harder to work with at the bench.
Why almost every white gold piece is rhodium plated
To get the bright, mirror-white finish buyers expect, most white gold — including much of the palladium-based kind — is finished with a thin plating of rhodium, another platinum-group metal, prized for its hardness and reflectivity. That plating is doing two jobs at once: it supplies the true white colour the underlying alloy may not fully have, and on nickel-based white gold it also puts a barrier between the nickel and the skin of anyone sensitive to it.
The plating is not the piece. It wears with handling, and as it thins the alloy underneath starts to show through — a nickel-based ring will look faintly yellow or grey again, which is exactly the colour rhodium was covering up in the first place. Replating restores it, though this site will not put a number on how often, because how long plating lasts depends entirely on how a specific piece is worn, and no honest average exists for that. Platinum has no plating to wear off, because there was never anything under it to hide.
How the two wear differently over decades
This is the more durable difference. When platinum is scratched, the metal is displaced rather than removed — it moves to the edges of the scratch rather than leaving the ring as dust. Over years this builds into a soft, matte surface many people call a patina, and the ring’s weight and the metal actually holding a stone’s prongs in place barely changes.
Gold, including white gold, genuinely loses metal when it scratches — fine particles are removed rather than pushed aside. It can be repolished back to a shine, but each polish removes a small amount of metal permanently, and prongs thin measurably over decades of wear in a way platinum prongs holding the same stone typically do not.
Weight
Pure platinum is considerably denser than pure gold — 21.45 g/cm³ against 19.32 g/cm³ — and alloying gold toward white with nickel or palladium, both lighter than gold itself, brings a white gold piece’s density down further still. The exact figure depends on which whitening metal a specific maker used, which this site has no way to know from a stamp alone, so no single white gold density is given here. What holds regardless of the exact alloy: a platinum ring of a given design will consistently feel heavier in the hand than the same design cast in white gold. The mechanics of comparing two metals by weight are in the metal density comparison.
Nickel and sensitive skin
Platinum at 950 is, for practical purposes, nickel-free. Nickel-based white gold is one of the more common triggers of nickel contact allergy in jewellery, which is covered in more detail in nickel allergy in jewellery — including why rhodium plating only masks the issue for as long as the plating lasts, and why palladium-based white gold sidesteps it at the alloy level rather than the surface.
Which of this matters more — the heft, the maintenance, or the skin question — depends on the person wearing it, and this site is not going to weigh those in for you.