The length of a bracelet to buy is determined by the size of the wearer's wrist and size of the beads in the bracelet. Larger beads mean that the bracelet should be longer to fit comfortably on the wrist. The average, traditional bracelet is 7 1/2 inches, 18 cm long.
Bracelets with very large beads may be 8 or 9 inches long. Here are wrist sizes for bracelets:
6 inches, 15 cm
6 1/2 to 7 inches, 17 cm
7 1/2 inches, 18 cm
The Collier or Collar Length: 14 inches 36/37cm. The Collier is made up of more than one strand of uniform Pearls that fit cosily around the base of the neck. A popular Coming-of-Age gift.
The Choker Length: 16 inches 40cm. The Choker is made up of one strand with large uniform sized Pearls that sits on the collarbone.
The Princess Length: 17 to20 inches 45/50cm. One of the most popular lengths the princess is well suited to crew and high necklines, but can equally add a frame to a plunging neckline.
The Matinee Length: 22 to 27 inches 56/69cm. The Matinee, an unrestricting length that looks great with casual or business wear, be it a sweater or the classic white blouse.
The Opera Length: 28 to 36 inches 70/91cm. The Opera Strand falls to the breastbone and usually consists of pearls larger than 8mm.
The Sautoir or Rope Length: 40 inches 100cm and over. The preferred length of necklace by the French haute-couture designer Coco Chanel. It's a lot of pearl, but very, very flexible in how and where it can be worn.
Rings are pretty difficult things to buy online but to get your size :-
Take a piece of string or cut a strip of paper no wider than 1/4".
Wrap the paper around the base of your finger and mark the string or paper where it meets.
Check that it slips over the joints of the finger without difficulty.
Measure the marked length of paper or string and compare it to the size chart. This should give you a good idea of your ring size. If your ring falls between sizes, order the next larger ring size.
Women’s rings typically range from size G to R. The most commonly purchased women’s ring sizes range from size K to N. Size M is the most popular ring size.
Men’s rings typically range from size P to Z. The most commonly purchased men’s ring sizes range from size R to U. Size T is the most popular ring size.
International Ring Size Chart