Comparison
9ct gold or Black zirconium?
Choose 9ct gold if you want a hallmarked gold ring that wears harder than 18ct and costs less. Choose black zirconium if you want a black ring with a hard surface that is grown, not plated.
- Heavier: 9ct gold, about 1.8 times the weight
- Harder surface: Black zirconium (Mohs 8 against 3.5)
- From: 9ct gold £515, black zirconium £199
- Resizing: 9ct gold, yes, by a jeweller; black zirconium, not usually
Checked .
| Side by side | 9ct gold | Black zirconium |
|---|---|---|
| Surface | Gold alloy, colour varies | Heat-grown black oxide |
| Hardness (Mohs) | 3.5 | 8 |
| Density | 11.4 g/cm³ reference | 6.5 g/cm³ reference |
| 6mm band, size N | about 5.5g | about 3.2g |
| Resizing | Yes, by a jeweller | Not usually |
| Hallmarked | Yes, by law above the exemption weight | No, not a precious metal |
| Our rings from | £515 | £199 |
Which is heavier, 9ct gold or black zirconium?
9ct gold is heavier, about 1.8 times the weight of black zirconium for the same ring. A 6mm band in size N comes to about 5.5g in 9ct gold and 3.2g in black zirconium.
| Width | 9ct gold | Black zirconium |
|---|---|---|
| 2mm | 1.8g | 1.1g |
| 4mm | 3.7g | 2.1g |
| 6mm | 5.5g | 3.2g |
| 8mm | 7.4g | 4.2g |
Worked out from the reference densities (11.4 and 6.5 g/cm³) with the same model as our ring weight calculator, where you can set your own size, width and thickness. A bigger size adds a little more metal: the size N page and the other size pages give the weights at each size.
Is 9ct gold more expensive than black zirconium?
Black zirconium costs less: 9ct gold rings start at £515 and black zirconium rings at £199 in our range. 9ct gold carries the cost of the precious metal itself, which is why it starts higher; black zirconium is priced on the making, not on bullion.
Every ring is made to order in your size, and engraving is free on every ring whose page offers it.
Which is harder wearing?
Black zirconium has the harder surface: Mohs 8 against 3.5 for 9ct gold, so it picks up fewer everyday marks. 9ct gold marks sooner, and any jeweller can polish it back.
9ct gold. 9ct is 37.5% gold and the harder of the two gold alloys, which matters more on a ring worn every day than the carat number does. All gold picks up marks with wear, and any jeweller can polish them out; polishing takes a very small amount of metal each time, so it is an occasional refresh rather than a routine. White gold is often rhodium plated, and a jeweller can replate it when it starts to look warm.
Black zirconium. The black is a hard ceramic oxide grown into the surface by heat, around Mohs 8, far harder than gold, so everyday knocks that mark a gold band leave it looking the same. It is scratch resistant rather than scratch proof: a hard blow against stone or steel can mark it, and a pale line is often metal rubbed off something else, which cleans away. Take it off for gardening, climbing and the gym, and if it is ever marked, our maker refinishes black zirconium depending on the damage.
Want the deepest gold colour? 18ct is 75% gold against 9ct's 37.5%. Compare 18ct gold and black zirconium
Can 9ct gold and black zirconium rings be resized?
9ct gold: Yes. A plain 9ct gold band can be made larger or smaller by a jeweller, the way wedding rings have always been resized. The exception is a band set with stones all the way round, where there is nowhere to cut without disturbing a stone, so on those the size is settled when you order.
Black zirconium: Not in the usual way. The black is grown into the surface of the metal, so cutting or machining the band would show bright metal underneath. That is why the size is settled before the ring is made, and every ring is made to that measurement.
Either way, getting the size right first is the easy part: the free ring size finder measures it at home in a couple of minutes, and the resizing guide explains the differences between metals.
Sensitive skin and hallmarks
9ct gold is a gold alloy, and white gold can be alloyed with nickel, so if you know you react to nickel, a hypoallergenic metal such as platinum, titanium or zirconium is the easy choice. Black zirconium is hypoallergenic and a common choice for sensitive skin. The metal allergy guide explains what causes a rash under a ring.
Gold, silver, platinum and palladium are hallmarked by law above the exemption weights. The marks go inside the band, where you can read the fineness for yourself. Titanium and zirconium are not precious metals, so there is no hallmark and none is required. Where a ring carries a solid gold inlay, that gold is hallmarked at Birmingham. The UK hallmarking guide explains each mark.
Our verdict
9ct gold if you want a hallmarked gold ring that wears harder than 18ct and costs less. Black zirconium if you want a black ring with a hard surface that is grown, not plated.
Not sure on width? The band width guide shows what each width looks like and weighs, and the metal chooser weighs the metals up against how you will wear the ring.
In these materials
Rings to look at
Rings made in, or available in, the two materials above, each with its current price, widths and finishes on its own page.
Slim band
Two millimetres of solid gold, narrow enough to sit close to an engagement ring.
Plain black zirconium
Black all the way round, and none of it is a coating.
Soft ridge
The face rises to a gentle ridge, so the light runs along the finger.
Explore the fit and weight
Common questions
- Is 9ct gold or black zirconium harder wearing?
- Black zirconium has the harder surface: Mohs 8 against 3.5 for 9ct gold, so it picks up fewer everyday marks. 9ct gold marks sooner, and any jeweller can polish it back.
- Is 9ct gold heavier than black zirconium?
- 9ct gold is heavier, about 1.8 times the weight of black zirconium for the same ring. A 6mm band in size N comes to about 5.5g in 9ct gold and 3.2g in black zirconium.
- Is 9ct gold more expensive than black zirconium?
- Black zirconium costs less: 9ct gold rings start at £515 and black zirconium rings at £199 in our range. 9ct gold carries the cost of the precious metal itself, which is why it starts higher; black zirconium is priced on the making, not on bullion.
- Can both be resized?
- Yes. A plain 9ct gold band can be made larger or smaller by a jeweller, the way wedding rings have always been resized. The exception is a band set with stones all the way round, where there is nowhere to cut without disturbing a stone, so on those the size is settled when you order. Not in the usual way. The black is grown into the surface of the metal, so cutting or machining the band would show bright metal underneath. That is why the size is settled before the ring is made, and every ring is made to that measurement.
- Are both hallmarked?
- Gold, silver, platinum and palladium are hallmarked by law above the exemption weights. The marks go inside the band, where you can read the fineness for yourself. Titanium and zirconium are not precious metals, so there is no hallmark and none is required. Where a ring carries a solid gold inlay, that gold is hallmarked at Birmingham.