Gemstone Buying Guide

Gemstones are precious stones that are commonly used as jewelries set on metals and in some cases used for investment. This guide aims to inform consumers on key characteristics in determining the quality of gemstones and the inherent attributes of particular gemstones.


In determining the quality of gemstones four main characteristics is observed, these are: cut, clarity, color and carat weight. These characteristics are not present in pearls where the attributes would reflect through size, color and shape.




Cut refers to how the particular gemstone is cut. An ideal cut would mean that the gemstone handles light and reflects as much of the light back to the viewer without leakage. The cut in a gemstone is what gives its brilliance. This is different in the case of pearls, pearls are not cut and their brilliance comes in the form of nacre thickness. Nacre is the natural layering of mollusks to foreign objects which leads to the projection of pearls. The thicker the nacre layering the more brilliant the pearl.




Clarity refers to the presence of blemishes and inclusions in gemstones. Clarity is one of the key determining factors in the value of a gemstone. Blemishes are categorized as surface flaws while inclusions are categorized as internal flaws. Inclusions are also present in pearls. This refers to surface blemishes such as cracks. This is not to be confused with the texture of natural or cultured pearls. Pearls have inherent tiny marks which is part of their natural texture.




Color refers to the color the particular gemstones. Although different gemstones would have different colors the colors should be rich and vibrant. Rich colors refer to gemstones not being too light or too dark. In the case of color changing stones the change in color should be a rich solid color. Three sub-attributes in color are hue, tone and saturation. Hue refers to the dominant color and the presence of additional colors especially in the case of color changing stones or stones with subtle colors. Tone refers to the lightness or darkness of the color. Saturation refers to the strength, purity or intensity of the hue inherent in the stone. In the case of pearls this will refer to both the body color and overtone that gives white pearls their overlying color.


Carat Weight:


Carat refers to the weight of the stone. A carat is equivalent to 0.200g. The consumer should be aware that carat weight refers to the weight and size of the stone and not to be confused with karat which is the measurement of the purity of gold. In the case of pearls this will refer to the size of the pearl measured in mm.




Gemstones come in varying shapes and to a large extent these shapes do not determine the value of these stones. Pearls are the exception to this rule wherein the value of the pearl is determined by the roundness of the pearl. The rounder the pearl the higher its value.


This is a list of different gemstones and a description on some of their intrinsic characteristics.


Agate: Is crypto-crystalline quartz that comes in colors of blue, yellow, green, orange, brown and gray. Some varieties of agate are known as swiss lapis, moss agate/ dendritic agate, onyx, agatized coral, petrified palm wood, dinosaur bone, sardonyx.


Alexandrite: Is a gemstone that is sought after due its ability to change color from green to red.


Amber: Characterized with translucent to opaque hues in colors of yellow, orange, red, crimson and brown.


Amethyst: Is a quartz stone that is characterized with purple or violet colors.


Ametrine: Ametrine possesses violet, purple and yellow colors and are distinguished by the presence of all colors on the stone.


Aquamarine: Characterized by blue and green-blue colors.


Aventurine: Semi-transparent quartz that is characterized by shades of green with silvery flecks.


Azurite: Copper ore that is opaque blue gem that is stripped concentrically with other shades of blue.


Beryl: Is a mineral and family name of well known gemstones. Characterized by different colors: green (emerald), aquamarine (blue-green), colorless (goshenite), pink (morganite), yellow (heliodor), red (bixbite).


Bloodstone: Chalcedony quartz that is characterized by dark green, opaque and translucent colors.


Benitoite: A rare blue stone with violet tints and undertones.


Chalcedony: Fine grained quartz characterized by gray, purple, white, green, blue, lavender, yellow and brown colors.


Chrysoberyl: A family of stones that include alexandrite and cats eye. Characterized by yellow, green, color changing, red, blue-green, green-yellow and brown colors.


Cat’s Eye: Characterized by yellow, green-yellow and yellow-green colors.


Chrysoprase: A variety of the Chalcedony that is characterized by its apple green color.


Citrine: Quarty characterized by yellow or orange color.


Carnelian: Characterized by opaque to translucent tones with colors of red, orange and brown.


Coral: Comes in tones of opaque or semi-translucent with colors of pink, cream, white, orange, red and black.


Emerald: Popular gems that are characterized by green color.


Garnet: A brilliant stone that changes color from red to blue.


Grossular: Yellowish-green stone belonging to the garnet group.


Heliodor: Stone characterized with the yellow color and considered to be a yellow beryl.


Hermatite: Opaque stone that resembles a polished metal found in colors of grey, blue and black hues.


Hiddenite: A kind of Spodumene is a light green gem with yellow undertones and sometimes come in colors of dark green.


Iolite: Clear violet-blue gem.


Jade: Popular opaque green gem.


Jasper: A variety of chalcedony quartz that comes in tones of red, brown, yellow, green and gray. This is an opaque gem that can be depicted as having solid, striped or spotted colors.


Kunzite: A kind of Spodumene is a clear gem that comes in shades of pink, pale purple, lilac and violet.


Lapiz Lazuli: A composite of different minerals that results in an opaque blue stone.


Labradorite: Dark opaque stone characterized by blue to green, yellow, orange and purple shades.


Malaia: Orange colored garnet with undertones of yellow, pink and red.


Malaschite: Copper ore that is opaque green gem that is stripped concentrically with other shades of green.


Marcasite: Opaque stone that resembles a polished metal found with reddish undertones.


Moonstone: Member of the feldspar gem family and characterized as a clear blue gem with a silver line running through or semi-translucent milky white with glittering white or blue running through it.


Morganite: A type of beryl that is characterized by pink, orange and purple tones.


Onyx: A chalcedony quartz characterized by ruddy brown layers with bands of dark brown.


Pearls: Formed through layering of nacre by mollusks on foreign bodies. Comes in different colors from white to black.


Peridot: Transparent gem characterized by shades of green and yellow.


Pyrope: A kind of garnet that is clear and colored red. This gem is sometimes confused for a ruby.


Quartz: A gem family that contains one of the largest varieties of gems.


Rhodochrosite: Carbonite material found in colors of orange, red and pink.


Rhodolite: A type of garnet that is characterized by a red color with strong purple undertones.


Rock Crystal: A type of quartz that is characterized by its clear, colorless and transparency.


Rose Quartz: A type of quartz that is characterized by its pink color.


Rubies: A variety of the corondium family that is popular due to its red color and sometimes blue undertones.


Sapphires: A variety of the corondium family that is popular due to its blue color and sometimes red undertones.


Sard: A chalcedony quartz that comes in brown, orange, apricot and red colors.


Scapolite: A gem that comes in a variety of colors from colorless to orange, yellow, light red, blue, green and violet.


Serpentine: Transluscent green gem that is sometimes misinterpreted as jade.


Smokey Quartz: Transparent quartz with colors that range from pale silver brown to dark lustrous smokey brown.


Sodalite: Dark blue semi-transparent gem that is sometimes substituted for lapis lazuli.


Spectrolite: Iridescent stone characterized by blue, green and purple hues.


Spessartine: A kind of garnet that is characterized for its yellowish-orange color.


Spinel: A gem that comes in a variety of colors of orange, yellow, red, green-blue, gray-blue, purple and violet.


Sugilite: An opaque gem that is characterized as red with purple undertones or purple with red undertones.


Sunstone: Iridescent stone characterized by red and orange hues.


Tiger’s Eye: A kind of quartz that comes in colors of brown, dark gold, amber and blue shades.


Topaz: A clear gem that comes in colors of brown, pale yellow, orange-brown, amber, pink-brown, red, blue, pale green, yellow-green, violet or colorless.


Tourmaline: A family of gems that are characterized for its variety in color and hardness quality that makes it suitable for any kind of jewelry.


Turquoise: An opaque blue gem that ranges in color from cerulean blue, dark cobalt blue and green-blue.


Zircon: Is a brilliant clear stone found in colors of colorless, red, orange, yellow and brown. This gem should not be confused with cubic zirconium. The latter is a synthetic composition while the former is a brilliant gem.


Zoisite: Known also as tanzanite can be found in colors of blue and green.



Now that the consumer is aware of the different characteristics and attributes of the various gemstones, the consumer should be aware on how to determine the store of their purchase as well. Below are some questions that the consumer should ask when they are determining the store they plan to purchase their gemstones from.


  • Credentials of Store – Is the store affiliated with any organization?
  • Knowledge of Salespeople – Do the salespeople share the same knowledge or are they unable to answer your questions? If it is the latter then it is best you avoid this shop.
  • Use of a loupe – If you brought a loupe do they allow you to inspect the gemstones? If you did not bring a loupe do they have a loupe for you to inspect the gemstones? If they won’t allow to you inspect the gemstone and they don’t have a loupe then you should avoid this shop.
  • Variety – Do they have a lot of variety of gems? Is there a large variety of quality as well? If the answer is yes then it is a good shop. If the answer is no and if you notice a large collection of bargain priced gemstones then it might be a good idea to look elsewhere.
  • Services – Do they provide cleaning and mounting services? What about jewelry customization? Generally speaking high quality gemstones are un-mounted which allows the consumer to inspect them thoroughly. Also check their policies on guaranties. If you are spending a lot of money on a high quality gemstone then you would want some sort of guarantee, and if the store is selling a high quality gemstone they would give you that guarantee. Make sure to read the guidelines of guarantees and return policy.
  • Does the store provide you with documentation of the gemstone in question? Is the gemstone lab tested? If it is do they allow you to contact the lab in order to confirm its quality? If not, do they give you a documentation of the gemstone and send the gemstone to be tested? If they say no to all of these then leave the store. There should be no problems in sending a gemstone to be tested.

In selecting the gemstone that the consumer wishes to procure they have to educate themselves in the characteristics of the stones, the credibility of the store and to their personal requirements and aesthetic tastes.