Person trying on a diamond ring helped by a jeweler at a store counter, focusing on their hands and the ring size chart.

Jewellery Sizing

July 7, 2023
Jewelry tips

At Istana, we always want to ensure that your pieces are the perfect fit. While coming to us is what we would always recommend, our below guide is the next best solution. 

How to measure necklaces

The total length of your necklace depends on several different factors, with personal choice being the most important. 

Lengths of necklaces are measured by taking the inner circumference with a ruler, or by measuring from end to end. In some cases, there is an extension of approximately 3cm. 

Jewellery Sizing Istana Jewellers necklace sizing

How to measure ring size

Istana Jewellers uses International Standard (ISO) for ring sizing, which is a measurement of the diameter of the rings. 

Below are a few options for measuring and determining your ring size should you choose to shop online. The below table will be able to help you convert your size into ISO. 

Please note that if you find yourself between sizes, we would recommend ordering a larger size. It is best to measure your finger at a normal body temperature as your fingers can shrink and expand when too hot or cold. If your knuckle and finger’s base are different sizes, take two separate measurements and choose a size in between. The ring should be able to fit over your knuckle but not be too loose that it will slide and move around on your finger. 

Lastly, if the band of the ring you are ordering is thick, please size up to allow for a more comfortable fit. 

This guide is for reference only. If in doubt, please reach out to us. Our team can also assist you with styling and any other questions. 

How to measure

If you measure the internal diameter of your ring (in mm), it should match with the corresponding size in the chart below. Be sure to use millimeters. 

Option 1 – The String Test:

  • Use a flexible measuring tape, or cut a piece of string, thread or ribbon. 
  • Wrap the tape snugly around your chosen finger. Ensure that the tape is not wrapped too tight and stretches which will skew your sizing – aim for a comfortable fit. 
  • Print our downloadable sizing chart
  • Compare your measurement with the downloadable sizing chart

Option 2 – The Secret Test: (The ultimate way to surprise your loved one!)

  • Print our downloadable sizing chart
  • Find a ring that your loved one currently wears
  • Make sure he or she wears that ring on the finger you are shopping for 
  • Place the ring on top of each circle until you find a perfect match 
ISO/CIRCUMFERENCE (MM) USA/CANADA UK & AUSTRALIA ITALY DIAMETER (MM)
47 4 H ½ 7 14.9
48 4 ½ I ½ 8 15.3
49 5 J ½ 9 15.5
50 5 ¼ K 10 15.9
51 45 ¾ L 11 16.3
52 6 L ½ 12 16.5
53 6 ½ M ½ 13 16.7
54 7 N ½ 14 17.1
55 7 ¼ O 15 17.5
56 7 ¾ P 16 17.7
57 8 P ½ 17 18.1
58 8 ½ Q ½ 18 18.3
59 8 ¾ R 19 18.8
60 9 ¼ S 20 19.0
61 9 ½ S ½ 20 19.4

How to measure bangle sizing

Carousel Bracelet in 18k Pink Gold with Black and Champagne Diamond Pave in Black Enamel

Measure your wrist with a flexible measuring tape, string, thread or ribbon. 

Use the below chart to reference bangle size to order.

Bangle Size Wrist Size
15 cm Fits up to 5.5″
16 cm Fits up to 6″
17 cm Fits up to 6.25″
18 cm Fits up to 6.5″
19 cm Fits up to 6.75″

How to measure bracelet sizing

Measure your wrist with a flexible measuring tape, string, thread or ribbon. 

*Please note that our bracelets come as a standard size of 7 inches. We are able to customize pieces in your desired length. 

Bracelet Length Wrist Size
6″ 5.5″
6.5″ 6″
7″ 6.5″
7.5″ 7″
8″ 7.5″