Comparison
18ct gold or 9ct gold?
Choose 18ct gold if you want the richest colour and the weight of 75% gold. Choose 9ct gold if you want a hallmarked gold ring that wears harder than 18ct and costs less.
- Heavier: 18ct gold, about 1.4 times the weight
- Harder surface: about the same (Mohs 3 and 3.5)
- From: 18ct gold £689, 9ct gold £515
- Resizing: 18ct gold, yes, by a jeweller; 9ct gold, yes, by a jeweller
Checked .
| Side by side | 18ct gold | 9ct gold |
|---|---|---|
| Surface | Gold alloy, colour varies | Gold alloy, colour varies |
| Hardness (Mohs) | 3 | 3.5 |
| Density | 15.7 g/cm³ reference | 11.4 g/cm³ reference |
| 6mm band, size N | about 7.6g | about 5.5g |
| Resizing | Yes, by a jeweller | Yes, by a jeweller |
| Hallmarked | Yes, by law above the exemption weight | Yes, by law above the exemption weight |
| Our rings from | £689 | £515 |
Which is heavier, 18ct gold or 9ct gold?
18ct gold is heavier, about 1.4 times the weight of 9ct gold for the same ring. A 6mm band in size N comes to about 7.6g in 18ct gold and 5.5g in 9ct gold.
| Width | 18ct gold | 9ct gold |
|---|---|---|
| 2mm | 2.5g | 1.8g |
| 4mm | 5.1g | 3.7g |
| 6mm | 7.6g | 5.5g |
| 8mm | 10.2g | 7.4g |
Worked out from the reference densities (15.7 and 11.4 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 18ct gold more expensive than 9ct gold?
9ct gold costs less: 18ct gold rings start at £689 and 9ct gold rings at £515 in our range. Both are precious metals, so the difference is mostly how much gold or platinum is in the ring.
Every ring is made to order in your size, and engraving is free on every ring whose page offers it.
Which is harder wearing?
They are close in hardness (Mohs 3 and 3.5), so they mark at much the same rate with daily wear.
18ct gold. 18ct is 75% gold, which gives it the deepest colour and real weight on the finger. It is a little softer than 9ct, so it shows marks a little sooner, and they polish out at any jeweller. Yellow and rose gold need nothing more; white gold is often rhodium plated, and replating brings back its bright white whenever you want it.
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.
Gold and scratches. 9ct is the harder of the two alloys, so it keeps its finish a little longer on a ring worn every day. Both polish back at any jeweller, and white gold can be replated whenever it starts to look warm.
Can 18ct gold and 9ct gold rings be resized?
18ct gold: Yes. A plain 18ct 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.
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.
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
18ct 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. 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. 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. The UK hallmarking guide explains each mark.
Our verdict
18ct gold if you want the richest colour and the weight of 75% gold. 9ct gold if you want a hallmarked gold ring that wears harder than 18ct and costs less.
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.
Soft ridge
The face rises to a gentle ridge, so the light runs along the finger.
Rounded court
Rounded outside and rounded inside, which is the comfortable one.
Explore the fit and weight
Common questions
- Is 18ct gold or 9ct gold harder wearing?
- They are close in hardness (Mohs 3 and 3.5), so they mark at much the same rate with daily wear.
- Is 18ct gold heavier than 9ct gold?
- 18ct gold is heavier, about 1.4 times the weight of 9ct gold for the same ring. A 6mm band in size N comes to about 7.6g in 18ct gold and 5.5g in 9ct gold.
- Is 18ct gold more expensive than 9ct gold?
- 9ct gold costs less: 18ct gold rings start at £689 and 9ct gold rings at £515 in our range. Both are precious metals, so the difference is mostly how much gold or platinum is in the ring.
- Can both be resized?
- Yes. A plain 18ct 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. 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.
- 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.