Connoisseur’s Guide to Buying Jewelry

When acquiring fine jewelry and gems, it’s important to consider some precautionary measures before making a significant purchase. Diamonds, gemstones, and pearls appear in an exceptionally wide range of quality and sizes, therefore prices vary greatly. Additionally, with the advances in technology, it’s virtually impossible for the untrained eye to detect some fabricated, enhanced, or treated stones.

Despite the potential pitfalls, there are steps you can take to gain greater confidence when making a purchase and to protect yourself from unknowingly buying a fake or treated gem.

  • First and foremost, purchase gems and jewelry from a reputable jewelry retailer, designer, auction house, or from a source that comes highly recommended from someone you trust.
  • Request a third-party diamond or gemstone report or certificate that outlines a stone’s quality, color, and cut. This is especially important when acquiring diamonds and colored gemstones such as rubies, emeralds, and sapphires, which are commonly treated to enhance color, clarity, and overall quality. Several reputable organizations, such as the Gemological Institute of America (GIA), provide this service. (See list of sources below.)
  • Don’t look for a return on investment. Historically, high-quality diamonds and gemstones have risen in price over the years, but there are no guarantees. Any industry expert will advise you to buy jewelry because you love it, not because you intend to make a profit one day.
  • Consider the auction houses for hard-to-find gems and contemporary designers. Many auction houses have expanded their jewelry offerings to include a wide selection of stones and contemporary designs, in addition to estate pieces. Also, auction houses have a team of in-house experts available to help you learn about jewelry, track down special requests, and advise on bidding. Take note: If a stone is not described in the catalog as natural, it is likely heat or laser treated or oiled to enhance its color and quality. It is common practice to treat high-quality rubies, emeralds, and sapphires, but a treated stone will obviously not command as high a price as a natural stone. You must inquire and have third-party documentation about the authenticity of piece.
  • Enlist a reputable jewelry consultant to help you track down rare stones, antique jewelry, or hard-to-find pieces from designers who don’t sell through typical retail stores but on a by-appointment basis. An industry expert will have direct access to the designer or manufacturer, and their educated advice can prove to be a valuable asset when making an important acquisition.
  • Get insurance. Once you have made a purchase, invest in adequate insurance to protect your assets. Just as you would an automobile or a home, it’s critical to insure high-quality jewelry.


When buying a diamond, the age-old four c’s — carat, cut, clarity, and color — remain the industry-wide parameters used to judge and price a stone. However, since two stones with the same description on paper can appear visibly different, it’s critical to assess the overall appearance of a stone. Always request an unbiased third-party appraisal report, which is common practice for most stones weighing one carat or more.

Colored Diamonds

Also known as fancy diamonds, colored diamonds are the by-products of negligible amounts of elements in the earth that alter the color of the diamond crystal. Yellow diamonds owe their color to nitrogen, sometimes combined with hydrogen; green diamonds are the result of irradiation from radioactive materials such as uranium; and the presence of boron creates a blue diamond. The rarest and most valuable color varieties are red, purple, green, and orange; pink, yellow, and brown diamonds are more common but are extremely scarce in intense shades and large sizes.

Due to the extraordinary values of these relatively small gems, it is important to seek expert advice when purchasing a significant colored diamond. Whether buying from an auction house, diamond dealer, or retail jeweler, it is imperative to obtain a gemological certificate to verify that the stone is natural and untreated. The value of a colored diamond depends primarily on the intensity of its color, which is graded on an industry scale that progresses from faint to fancy vivid. Because there are parameters within these designations, it is helpful to make side-by-side comparisons with other similarly graded stones to assess a particular gem’s color saturation.

Kimberley Process

In November 2002, the Kimberley Process Certification Scheme (www.kimberleyprocess.com) was created to combat the flow of conflict diamonds. Conflict, or blood, diamonds are rough diamonds from African countries that are used by illicit or rebel forces to finance wars. The Kimberley Process provides guidelines for rough-diamond trading to be regulated by countries, regional economic groups, and diamond-trading groups to guard against conflict diamonds entering the legitimate trade. Participants are required to implement internal controls, and all shipments of rough diamonds must be accompanied by a Kimberley Process certificate. It is estimated that Kimberley Process participants account for approximately 99.8 percent of the global production of rough diamonds.

Colored Gems

Colored gems come in a remarkably wide variety, and prices are dictated by a gem’s quality, availability, and desirability. Rubies, emeralds, and sapphires are among the most commonly known precious collectible gems, but today’s sophisticated designers are also using lesser-known gems such as bright blue paraiba tourmaline, green tsavorite garnet, and lavender spinel. Like high-quality rubies and sapphires, these gems also command top dollar.

When considering an important colored-gemstone acquisition, it’s more critical to gain an understanding of acceptable treatments and certified natural gemstones. Even the most prominent jewelry houses will accept certain treatments that improve the color of gem. However, they steer clear of any process that changes the color of a stone, masks inclusions or flaws, or increases the weight of gem.

Connoisseurs should expect to pay top dollar for a natural stone of any reasonable size. A sizeable untreated ruby, according to industry sources, could command 10 times that of the price for a slightly treated stone.

It’s critical to consult a third-party gemology lab such as the GIA or the American Gem Society before acquiring an important stone. While some treatments are acceptable, you must know what you are buying to assess the appropriate value of gemstone.

Phenomenal stones

Gems that exhibit a color change in differing light or a flash of light are known as phenomenal stones. In high qualities and large sizes, phenomenal stones are a rare collectible. A prime example is the highly desirable alexandrite, which changes from red in incandescent light to green in daylight. Other phenomenal stones are cat’s eye chrysoberyl and star sapphire, which both have natural silky fibrous inclusions that when lined up just right reflect the light to create a star or a band of light.


Most pearls today, including the finest South Sea and Tahitian, are cultured. Exceptional cultured pearls can command upwards of $100,000 a strand because the labor and resources required to cultivate the delicate oysters in pristine waters is an expensive and risky business. A natural disaster, like a tsunami, can decimate an oyster farm.

The value of a pearl is assessed on color, luster, orient, texture, and shape. Aside from natural pearls, which are typically found in old jewelry, the most expensive cultured pearls are smooth, perfectly symmetrical, and matching strands of Golden South Sea and White South Sea. Tahitian pearls are also highly desirable.

Natural Pearls

The finest natural pearls originated in the Persian Gulf, but those resources have long dissipated as a result of over-farming and environmental pollution. Most natural pearls available today are from old jewelry, and they command top dollar. There are some naturally occurring pearls such as freshwater seed or stick pearls found in river mussels, but they are not as expensive as perfectly symmetrical, round pearls.

Pearl Treatment

Pearls are commonly dyed in a variety of colors, so it’s critical to obtain a third-party report to verify that an expensive strand of cultured pearls is not color treated or coated.


There are several industry organizations that grade and value diamonds, gemstones, and pearls. Here are a few:

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