The luster of any pearl, whether natural or cultured, depends on the thickness of the nacre. If the nacre is thin, the pearl will look chalky and dull; a pearl with thick nacre will appear ‘metallic’ and exhibit a reflection.

It is best to view pearls in natural light. Fine quality pearls exhibit iridescence. For example, a Tahitian grey pearl may have overtone hues of lavender, pink and olive greens—called ‘peacock’. A lustrous, even color, without blemishes and perfectly round is the most valuable.
The value will be diminished when a pearl is not completely smooth and has slight nicks, wrinkles, scratches, cracks, pits, dimples, bumps in the nacre, known as surface blemishes. 

A perfectly round pearl is the most valuable of all. The Japanese Akoya form round pearls more often than any other type of oyster. There are many oval shaped pearls that may appear round; the price of a slightly oval pearl will be considerably less.

Many different shapes of pearls, depending on the type of oyster and the type of nucleation, are found all over the world. A Baroque shape refers to a pearl that is not round, but has an irregular shape with uneven surfaces. Examples of baroque shapes are called pear, rectangular, square, egg, button, wings and coin.
Tahitian pearls can be round, semi-round, drop, button, baroque and circle (rings around the pearl). South Sea pearls are round, semi round, circle and baroque. Freshwater pearls are mostly baroque and come in endless varieties of shapes, often flat as rather than spherical.

A blister pearl is a natural or cultured pearl that is attached to the surface of the shell, when they are removed from the shell they are flat on one side and covered in nacre on the top. Mabe pearls are a cultured blister pearl with a round top and tend to be very delicate. Seed pearls are very small natural pearls usually 2mm round. Keshi pearls are a byproduct of the oyster, a small pearl that can form in the muscle of the oyster in addition to the cultured pearl. They can be flat, oval, odd-shaped and usually has a poor luster quality.


Melo melo pearls are produced by the melo gastropod genus of sea snails. They are non-nacreous, composed instead of calcite and aragonite, which gives them a smooth porcelain luster and sometimes a flame pattern across the surface. 


When choosing a strand of pearls, the first thing to look for is matched size, color, roundness and luster. Pearls are traditionally strung on a special silk cord from Japan that are usually tied with a tiny knot in between each pearl to keep them separate and secure.


When pearls are worn over the years the thread will stretch, if the pearl slides on the thread, it is an indication that it is time to have the pearls taken apart, cleaned and restrung. A 16” strand is called a choker; 18” strand a princess; 20” a matinee and 32” an opera. Any strand longer than opera is called a rope of pearls.

Pearls are a delicate gem that can easily be damaged or destroyed with perfumes, hair sprays and oils from skin. The nacre, or surface of the pearl, will dissolve from acids.

Pearls should never be worn in water such as hot tubs, swimming pools or showers. Extreme heat can crack the nacre, if left in the sun or by a heater.

Pearls need to be cleaned with a soft, damp cloth, without the use of any detergents or cleaners. Never use any type of abrasive cleaners or abrasive materials or the pearl surface. 
Do not put pearls in ultrasonic cleaners or commercial jewelry cleaners.

A damaged pearl can never be repaired because the nacre cannot be replaced. Pearls should be stored in a soft pouch or pearl folder. Safekeeping and treatment of pearls will ensure that pearls can last for generations.

Janet Deleuse 

For more information call us: 415-459-3739 

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“Janet, thank-you for everything you do. As I said before, you are truly an artist, and that is why it is so special buying jewelry from you.” Peter, Atlanta, GA

” Beauty, exquisite design, pleasant and personalized attention. These qualities have been constant in our 20 years of shopping with Janet and Jeff Deleuse – Two exceptionally talented and caring people. The Best!’ Helen P.,Belvedere

"This store has a very pleasant environment and Jeff and Janet are both kind, wonderful people. I used Jeff a few times for appraisals and he was very thorough and was happy to answer lots of questions. He uses scientific methods and tests rather than going solely by appearance as some jewelers will try to do, and his expertise is well respected. On one occasion, he even went out of his way to help expedite a deal for me. He has my highest recommendation. Suzanne T., San Rafael, CA

“Jeff is an incredible gemologist who knows everything there is to know about gem stones. He is a true professional and can be trusted. The quality of their work is impeccible and always consistent. I would recommend Deleuse Jewelers to anyone looking for a new, “bauble,” for themselves or someone special!” Terri B., Ross

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"I purchased this beautiful chain from Janet Deleuse about 3 weeks ago. It was an online purchase so I was hoping I would be pleased. It exceeded my expectations as it was exactly as pictured. Delicate and perfectly crafted. Packing was very secure and shipping was quick. I would not hesitate to purchase from Deleuse again! Michele, New Jersey

“Janet and Jeff designed and crafted our wedding rings and did a great job. They worked with existing diamonds we had in an antique ruby cocktail ring, added the sapphire stone and made a beautiful pendant with the ruby. In addition, they designed earrings for our daughters. All are still in great shape today. They are easy to work with and very reliable and trustworthy.” Peg M., San Anselmo

Accreditation includes diplomas from the Gemological Institute of America and the American Gem Society and thirty years of experience.

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