You should always buy the pearl size that you like. However, pearls are steeped in tradition from the time when only the rich and royalty could afford a glorious necklace of matched pearls. If you like to buck trends, by all means do it! If you want to go with tradition, follow these guidelines:

Pearl size by age and station

- 5.5 mm-6 mm These tiny pearls are traditionally worn by girls ages 12 to 16 or very small women.

- 6.0-6.5 mm This size is the perfect gift for graduations or 16th birthdays. They are traditionally worn by young women ages 16-24.

- 6.5 mm-7.0 mm A strand of this size is considered the "starter" set for women in their mid 20s on up. It is the traditional birthday, Christmas and Valentine's Day present.

- 7.5 mm-8.0 mm This size, traditionally worn by women age 30 and up, is the strand for the upwardly mobile woman. Not too flashy, 8 mm is big enough to give an air of importance. This size is a traditional wedding or anniversary gift through the fifth year of marriage.

- 8.0 mm-8.5 mm These pearls tend to be more expensive, so they are traditionally worn by women age 35 and up, and often signify financial success.

- 8.5 mm-9.0 mm A strand of this size are perfect for women ages 35 to 45 or a woman in her early 30s of high stature. They exude class. Jacqueline Kennedy's famous pearls were this size.

- 9.0 mm-9.5 mm These are very high-end pearls are traditionally worn by women in their later years. You'll find these pearls in the jewelry boxes of wealthy women or dedicated pearl collectors.

- 9.5 mm-10.0 mm Pearls are rarely found in this size and even harder to match well, so they fetch a very high price on the jewelry market. Former First Lady Barbara Bush owns pearls this size.