It is suggested to choose according to the individual's body shape, age and wearing occasion. Generally speaking, 6.5-7.5 pearl necklaces are too small for young ladies, such as 20-30 years old. 7.5-8.5mm pearl necklaces are all medium-sized, depending on the individual, some feel small and some feel medium. Suitable for women aged 30-40, and can be worn in general occasions. 8.5-9.5mm pearl necklace is a little big, suitable for elders to wear, or important occasions, weddings, banquets, a little atmospheric, not too small. Pearl necklaces over 9.5- 10.5mm are more luxurious, and can be worn on important occasions or high-status occasions! I hope I can help you and adopt it. Thank you!