15 refers to a ring with an inner ring diameter of 18.0mm and a circumference of 56.5 mm.
Usually, warning indicators include letters and numbers, with letters representing metal composition (silver: S, gold: Au or K, platinum: PT, diamond: D) and numbers representing purity.
For example, S925, S stands for silver, which means silver, S925 stands for 925, and 925 stands for purity of 92.5%.
Such as PT950, PT stands for platinum, and 950 stands for purity of 950‰.
Extended data
Measurement method of ring size
1. Wrap a large piece of paper around the finger of the ring you are wearing.
2. There are pen marks at the intersection, which are enclosed with paper.
3. After the paper strip is polished, the data measured by the grid gauge is the circumference of the ring to be purchased.
4. Check the number of rings according to the circumference.