Pearls add an aura of sophistication and beauty to any outfit, whether it is a bride's wedding dress, a woman's formal evening dress, a formal blouse, or even a girl's communion dress. Their round shape and white or cream colour compliment virtually any wardrobe.

But how does one compare the pearl jewellery being offered by different retailers, and ensure you are getting the best value for your money?

When shopping for pearl jewellery such as pearl necklaces or pearl bracelets, it is important that you realize what you are buying, and how retailers grade their pearls. This will allow you to fairly compare pieces, without being distracted by deceptive advertising lingo.

You should first realize that virtually all pearls available on the market today are cultured freshwater pearls. Many stores will simply advertize "pearl" or "freshwater pearl" or "cultured pearl", but suffice to say, they are all cultured freshwater pearls. Natural pearls are extermely rare (mostly due to pollution) and are priced accordingly. Those looking for information on natural pearls can look for an upcoming article at http://www.crater.com/articles. Unless you know how to tell the difference, you are advised to assume all pearls are cultured freshwater pearls and buy accordingly. The remainder of this article relates to cultured freshwater pearls.

Luster This is the gloss, sheen, or brightness that you see. Low quality pearls will appear dull, with a matte finish. High lustre pearls will appear nearly brilliant, with exceptional pearls having an almost glassy, mirror-like surface.

Surface / Nacre Pearls are made of layers of a substance called Nacre. Pearls are caused by irritants inside the shells of various mollusks. High quality pearls have a very small irritant (such as a grain of sand) and are virtually all nacre. Low quality pearls have a large irritant (such as a chunk of mother-of-pearl) and relatively little nacre. Low quality pearls may also have inclusions or imperfections in the pearl's surface. High quality pearls have no visible inclusions.

Shape The most highly prized pearls are those which are perfectly spherical to the naked eye. Pearls that have a slightly oblong shape (like a football, or an oval) are of average value, and still beautiful on the appropriate piece of jewellery. Pearls that are randomly shaped or having a wavy surface are lower grade, but they can still look beautiful when properly strung or arranged.

• Round Round pearls are the most expensive variety. They are truly spherical and will roll in a straight line. Very few pearls fall into this category, but they often include pearls that are nearly round.
• Semi-Baroque These pearls have symmetrical shapes, but are not truly round. These include tear-drop, oval, or rondelle.
• Baroque These pearls have an irregular shape. Though generally less expensive, some unique-shaped specimens can fetch a higher price than round pearls. Baroque pearls have been made into famous or important jewellery pieces throughout history.

Colour The colour of the pearl has some bearing on the value of the pearl jewellery, but this factor is mostly in the eye of the beholder. Cultured freshwater pearls come in a range of colours including whites, creams, pinks, lilacs, silver and gold shades. Black pearls are even available from Tahitian black-lipped oyster. Pearls are sometimes dyed to achieve a particular colour. Colour is mostly a personal choice and is also dependant on the desired use of the jewellery, but when comparing two identical pieces, the one that is naturally coloured (not dyed) has more value than the one which is dyed.

Size In general, the larger the pearl size the more valuable it is. This is generally because the larger the pearl size, the pearl would have had to remain in the mollusc longer, increasing the pearl farmer's investment.

Grading Table The following table uses one common method of grading pearls. Many different grading lists exist, making it difficult to compare pieces from different manufacturers. But if you keep in mind the actual meaning of the points above (luster, matching, shape, nacre, colour) you can make an informed decision. The gradings here are a guideline, and should not be used as a concrete rule that all retailers follow. It can be used to help you mentally compare multiple pieces, to compare their value.

• AAA These pearls are perfectly round to the eye. They have an excellent lustre, very clean nacre (95% nacre) with no surface inclusions. Jewellery claiming to be this grade will have excellent matching between pearls. Pearls from this grade represent the top 1% of a pearl harvest.
• AA+ These pearls are visibly round with excellent lustre. They have clean nacre (95% nacre) with no surface inclusions. There is excellent matching between pearls. Pearls from this grade represent the top 5% of a pearl harvest.
• AA These pearls are near-round to off-round. They have a good lustre with a good nacre (80-90% nacre) with no surface inclusions. There is good matching between the pearls. This grade represents the top 15% of a pearl harvest.
• A/A+ Off round to baroque in shape, this grade of pearl has a moderate lustre and is composed of about 70% nacre. It has no surface inclusions. Jewellery claiming to be this grade had good to moderate matching.
• A This grade represents pearls that are very off-round to baroque. They have moderate to low lustre, with moderate to heavily blemished nacre. There is moderate matching between pieces.
• Commercial/Beading quality Pearls of this grade are asymmetrical baroque, with moderate to low lustre. They display heavily blemished nacre with heavy inclusions. There is poor to moderate matching between pieces. Most pearls of this grade are ground up for use in commercial use such as makeup.