1, soft ruler measurement: measure the size of the jade bracelet, that is, measure its ring mouth or measure its inner diameter. Put your thumbs together so that the tip of your thumb is close to the root of your little finger, then wrap a soft ruler around the widest part of your palm, tighten it and record the measurement data. Divide this data by 3. 14 to get the inner diameter of the jade bracelet.

2. Vernier caliper measurement: put the palm flat so that the thumb and forefinger are at 90 degrees, and measure the width of the metacarpal joint with vernier caliper. Corresponding to the inner diameter of the jade bracelet, the width above 82 mm corresponds to the inner diameter above 60 mm, 74 ~ 78 mm corresponds to 56 ~ 58 mm, 70 ~ 74 mm corresponds to 54 ~ 56 mm, 66 ~ 70 mm corresponds to 52 ~ 54 mm, and 62 ~ 66 mm corresponds to 50 ~ 52 mm.