Ring sizing is one of the most common concerns when buying an engagement ring — especially when the proposal is meant to be a surprise. The good news is that there are several reliable ways to find out your partner's ring size without giving the game away, and if you don't quite get it right, resizing is a straightforward process.
At JQ Diamonds, we offer lifetime resizing on all rings purchased from us. So even if your estimate is slightly off, it's never a problem.
How Ring Sizes Work
In the UK, ring sizes are denoted by letters — A through Z, with half sizes available (for example, L½). The most common sizes for women are J to P, with L and M being the most frequent. The most common sizes for men are P to T.
Ring sizes refer to the internal circumference of the ring. A size L ring has an internal circumference of approximately 48.7mm. Each full size represents a change of roughly 1.25mm in internal diameter.
It's worth noting that finger size can vary throughout the day — fingers are typically slightly larger in the evening and in warm weather, and slightly smaller in the morning and in cold conditions. A well-fitting ring should slide on with gentle resistance and come off with a little effort. It should not spin freely or leave an indent.
How to Find Your Partner's Ring Size Secretly
Method 1: Borrow an existing ring
This is by far the most accurate method. If your partner already wears a ring on their ring finger — or any finger of a similar size — borrow it and bring it to us. We can measure it precisely in store in seconds. If you can't bring it in, you can trace around the inside of the ring on paper and bring that instead, or measure the internal diameter with a ruler (the distance straight across the inside of the ring).
Method 2: Ask a friend or family member
A trusted friend or sibling may already know — or may be able to find out naturally in conversation without arousing suspicion. This is particularly effective if they are in regular contact with your partner.
Method 3: Use a ring sizer while they sleep
This sounds more dramatic than it is. A simple ring sizer tool — a set of graduated rings — can be gently placed on your partner's finger while they are asleep to find the closest match. We can provide a ring sizer if you visit us in store.
Method 4: Compare finger sizes
If you know your own ring size, you can compare the size of your fingers to get a rough estimate. Alternatively, press your partner's finger gently into a bar of soap or a piece of mouldable putty to leave an impression, then measure the diameter of the impression.
UK Ring Size Chart
The following are the most common UK ring sizes for women's engagement rings, with their corresponding internal measurements:
- J — 15.9mm diameter / 49.9mm circumference
- K — 16.3mm diameter / 51.2mm circumference
- L — 16.7mm diameter / 52.5mm circumference
- M — 17.1mm diameter / 53.8mm circumference
- N — 17.5mm diameter / 55.1mm circumference
- O — 17.9mm diameter / 56.3mm circumference
- P — 18.3mm diameter / 57.6mm circumference
If you are ordering online and cannot determine the size with confidence, select M as a starting point — it is the most common size and will give us a good base for resizing.
What If the Ring Doesn't Fit?
Don't worry — this happens regularly and it is always fixable. Most rings can be resized by one to two sizes in either direction without any visible change to the ring. Settings with stones that run continuously around the band (such as full eternity rings) are more complex to resize, but your specialist will advise you at the point of purchase.
For all rings purchased from JQ Diamonds, we offer lifetime resizing as standard. For rings purchased elsewhere and brought to us for resizing, a fee will apply depending on the metal, the extent of the alteration, and the complexity of the setting.
In twenty years of fitting engagement rings, I have never once seen a proposal ruined because the ring was the wrong size. It's always fixable — and it's never what people remember.
JQ Diamonds, In-House Goldsmith
Visit Us for a Free Ring Sizing
Come into our showroom and we'll size both of you in minutes.
Frequently Asked Questions
Can I order a ring without knowing the size?
Yes. If you order online and are unsure of the size, simply leave a note at checkout or contact us and we will discuss the best approach. For bespoke commissions, we strongly recommend confirming the size before we begin crafting.
How long does resizing take?
Most resizing jobs take between 5–10 working days. For urgent cases, speak to our team and we will do our best to accommodate you.
Will resizing damage the ring?
No — when done properly by a skilled goldsmith, resizing is invisible. Our in-house goldsmith carries out all resizing in our Birmingham workshop.
Is there a charge for resizing?
For rings purchased from JQ Diamonds, resizing is included for life at no charge. For rings from elsewhere, we charge a fee based on the work required — typically £40–£120 depending on the metal and complexity.
