Pearl sizes vary depending on the type of oyster or mussel that they come from. Generally speaking the pearl size is one of the most important factors of value, although color suchs as pink, black, and whites, can also influence price. Naturally, the larger the pearl, the more valuable it is. The reason behind the size of the pearl can be of many factors, mainly the time the mollusk was under water but there are several other factors. These include the oyster pearls health of the mollusk, the size of its nucleus, climate, and nutrients in the water, and or pollution. Pearls are usually between 2mm to 20mm, these are of course extremes on both ends. Some are known to reach a size of 50mm in length! Refer to the chart below to get a good idea about sizes.
As you already know pearls come in different sizes, but they are also shaped differently. The peal shapes range from a near perfect round to sticks and even crosses all of which can be used to make a pearl necklace or other pearl jewelry! A well shaped symmetrical pearl is far more valuable than an irregular one. This is not to say that irregular pearls are worthless, in fact, they are popular in recent times and used to make some very spectacular pearl jewelry. Check out the pearl type section to learn about the different types of pearls in our pearl education section!
Average sizes for pearls on the market today are around 7 to 7.5mm. The pinctada Fucata is the scientific name for the oyster that produces akoya pearls, also know as sea pearls. Sizes for akoya pearls are average from 6-8.5mm. Any akoya pearl over 8mm is considered to be rare. In general you'll commonly find an akoya pearl necklace in the 6-7.5mm range.
There are currently over 350 species that can produce freshwater pearls. The freshwater mussel Hyriopis Cumingii is probably the most responsible for production of these types of pearls. They are most commonly found in the waters of Japan and China. Common sizes of Freshwater Pearls are from 3-7mm, however, there are extremities on both sides. Freshwater Pearls can even reach 18mm!
Just by its name you can tell that Pinctada Maxima means something big! This is indeed the world's largest producing pearl oyster. You may hear other names for this oyster such as silver or golden lipped oyster which are also accurate. Pearls can sometimes get over 22mm! Not quite big enough to play soccer with but still a hefty feat for nature! Cultured South Sea pearls are the end product and will be responsible for burning a hole in may peoples pockets as these pearls are among the rarest and most expensive on the market.
A typical Tahitian pearl necklace, pearl earrings, and pendants are other works of art that the Pinctada Margaritifera takes credit for. It becomes adult after 3 years old and produces average pearls from 8mm-14mm. It wasn't until the 1970s that Tahitian pearls became popular. The colors produced by these pearls are magical and among the most respected in the industry.