Ultimate Guide To Gemstones

The 4C's of Gemstones

Buying a gemstone is often a very different experience than buying a diamond. Gemstones are bought based on favorite colors, wardrobe matches, personality, and fashion trends. While gemstones are judged using the 4Cs, just as diamonds do, each is judged separately. For example, a sapphire is compared to another sapphire, but wouldn't be compared to an emerald or aquamarine. Choose your gemstone jewelry based on your personal preferences. 

Shape


London Gold sells a number of different shaped gemstone jewelry. Some of our most popular shapes include round, marquise, oval, pear, princess, and baguette. 
Diamond ShapesDiamond Shapes


Cut

Gems are cut in a variety of different ways. Transparent stones will often be cut with facets. Unlike diamonds, the facets are planned to maximize the color. Other stones like jade, opal, and onyx will be cut into a smooth domed shape known as a cabochon. While still other stones like cameos are intricately carved. 
Diamond Cuts


Color

Gemstone color is different from judging the color of a diamond. Every gemstone has a range of color that runs from light to dark and more vivid to less vivid, with a small range of color considered preferable. All of the families of color are represented by gems of different types.

  • Red Mozambique, Garnet, Ruby,
  • Pink Rhodolite, Garnet, Pink Sapphire  
  • Yellow Yellow Sapphire, Citrine
  • Green Bloodstone, Emerald, Jade, Peridot
  • Blue Aquamarine, Blue Chalcedony, Blue Spinel, Blue Zircon, Lapis, Blue Sapphire
  • Purple Amethyst, Tanzanite
  • White Akoya Pearl, Freshwater Pearl, Mabe Pearl, South Sea Pearl, White Spinel, White Topaz, Moissanite, Opal
  • Brown Smoky Quartz
  • Black/Gray Tahitian Pearl, Onyx  


Clarity

Gems also have internal characteristics called inclusions. Some gemstones are known for having many inclusions like emerald or for having few inclusions like citrine. Each gemstone will be graded for clarity differently.

Like diamonds, gemstones are measured using carats. A carat is equivalent to .2 grams or .007 of an ounce. Unlike diamonds, each gemstone has a different density which greatly contributes to the weight of the stone.


Diamond & Gemstone Size Ranges

We take pride in offering great value and quality. In order for us to offer this value, it is necessary to buy and sell diamonds in weight ranges. To help assist you in understanding these ranges, we have provided the following chart of size tolerances.

accent
.004 min.
0.01
.008 min.
0.015
.012 min.
0.02
.015 min.
0.025
.02 min.
0.03
.025 min.
0.04
.035 min.
0.05
.045 min.
0.06
.055 min.
0.07
.065 min.
0.08
.075 min.
1/10
0.09 min.
1/8
.11 min.
1/6
.14 min.
1/5
.18 min.
1/4
.23 min.
1/3
.29 min.
3/8
.37 min.
1/2
.45 min.
5/8
.60 min.
3/4
.66 min.
7/8
.84 min.
9/10
.90 min.
1
.96 min.
1 1/8
1.10 min.
1 1/6
1.14 min.
1 1/5
1.18 min.
1 1/4
1.23 min.
1 1/3
1.29 min.
1 3/8
1.37 min.
1 1/2
1.45 min.
1 5/8
1.60 min.
1 3/4
1.66 min.
1 7/8
1.84 min.
1 9/10
1.90 min.
2
1.96 min.
2 1/8
2.10 min.
2 1/6
2.14 min.
2 1/5
2.18 min.
2 1/4
2.23 min.
2 1/3
2.29 min.
2 3/8
2.37 min.
2 1/2
2.45 min.
2 5/8
2.60 min.
2 3/4
2.66 min.
2 7/8
2.84 min.
2 9/10
2.90 min.
3
2.96 min.
3 1/8
3.10 min.
3 1/6
3.14 min.
3 1/5
3.18 min.
3 1/4
3.23 min.
3 1/3
3.29 min.
3 3/8
3.37 min.
3 1/2
3.45 min.
3 5/8
3.60 min.
3 3/4
3.66 min.
3 7/8
3.84 min.
3 9/10
3.90 min.
4
3.96 min.
4 1/8
4.10 min.
4 1/6
4.14 min.
4 1/5
4.18 min.
4 1/4
4.23 min.
4 1/3
4.29 min.
4 3/8
4.37 min.
4 1/2
4.45 min.
4 5/8
4.60 min.
4 3/4
4.66 min.
4 7/8
4.84 min.
4 9/10
4.90 min.
5
4.96 min.
5 1/8
5.10 min.
5 1/6
5.14 min.
5 1/5
5.18 min.
5 1/4
5.23 min.
5 1/3
5.29 min.
5 3/8
5.37 min.
5 1/2
5.45 min.
5 5/8
5.60 min.
5 3/4
5.66 min.
5 7/8
5.84 min.
5 9/10
5.90 min.
6
5.96 min.
6 1/8
6.10 min.
6 1/6
6.14 min.
6 1/5
6.18 min.
6 1/4
6.23 min.
6 1/3
6.29 min.
6 3/8
6.37 min.
6 1/2
6.45 min.
6 5/8
6.60 min.
6 3/4
6.66 min.
6 7/8
6.84 min.
6 9/10
6.90 min.
7
6.96 min.

There are a variety of metals choices available for jewelry. Whether you like the allure of platinum or the range of options with the classic gold, you will find a number of stylish pieces, sometimes even combining the two metals. Today, alternative metals like sterling silver, titanium, and stainless steel give you additional options in look, strength, price, etc. Each choice has its own qualities, so base your choice on the ones that you value most.

Platinum 

Platinum is generally 95% pure and does not tarnish or lose its rich white luster. Platinum is the heaviest of all the precious metals weighing approximately twice as much as karat gold. Its purity makes it hypoallergenic, perfect for people who are sensitive to the alloys used in gold. Platinum is also known for its strength and pliability, just one gram of platinum can drawn into a fine wire over one mile long.

Gold

Pure 24 karat gold is rarely used in jewelry because it is too soft for frequent wear. Gold is mixed with alloys like copper, silver, nickel, and zinc to give different colors, strength, and durability. Gold's purity is measured in karats, which indicate out of 24 parts how many parts are gold. For example, 18kt gold contains 18/24 gold and 6/24 alloy, while 14kt gold contains 14/24 gold and 10/24 alloy. Gold is traditionally seen in yellow and white colors, but can also be available in rose or green on occasion.

Sterling Silver 

Sterling silver is usually 92.5% silver and 7.5% copper. Silver is much more plentiful than platinum or gold and is much less expensive. It takes on a much higher polish than any other metal, but it does tarnish. The tarnish can be removed, but silver requires much more care than other metals.

Titanium

Titanium is a light, strong, and corrosion-resistant metal. Titanium offers you seven times the strength of platinum at about 1/3 of the weight. It is the hardest natural metal on earth and therefore offers more scratch resistance than gold or silver. In addition, titanium is also hypoallergenic. When ordering titanium rings, be extra sure about your ring size. The biggest drawback of titanium rings is that they cannot be sized by traditional ring sizing methods.

Stainless Steel 

Stainless steel is a low cost alternative to traditional metals. It is naturally hypoallergenic and will not rust or tarnish. Stainless Steel will not break or bend under normal usage and is stronger than any other alloy.

Gemstone Enhancement Codes

Published by the American Gem Trade Association.

Enhancement: Any treatment process other than cutting and polishing that improves the appearance (color/clarity/phenomena), durability, or availability of a gemstone.

N: The "N" symbol appears on the chart only for natural stones which are not currently known to be enhanced; however, the "N" symbol can also be used for other natural gemstones in the event that a gemstone has received no enhancement and the seller will provide a guarantee that there has been none.

E: The "E" symbol indicates that a gemstone has undergone its traditional enhancement process.

B Bleaching                                                              

The use of heat, light and/or other agents to lighten or remove a gemstone's color.

C Coating

The use of such surface enhancements as lacquering, enameling, inking, foiling, or sputtering of films to improve appearance, provide color, or add other special effects.

D Dyeing

The introduction of coloring matter into a gemstone to give it new color, intensify present color or improve color uniformity.

F Filling

The filling of surface-breaking cavities or fissures with colorless glass, plastic, solidified borax or similar substances. This process may improve durability, appearance, and/or add weight.

H Heating

The use of heat to effect desired alteration of color, clarity, and/or phenomena (if residue of foreign substances in open fractures is visible under properly illuminated 10X magnification HF should be used.

HP Heat & Pressure

The use of heat and pressure combined to effect desired alterations of color clarity and/or phemonena.

I Impregantion

The impregnation of a porous gemstone with a colorless agent (usually plastic) to improve durability and appearance.

L Lasering

The use of a laser and chemicals to reach and alter inclusions in diamonds.

O Oiling/Resin Infusion

The filling of surface-breaking fissures with colorless oil, wax, resin, or other colorless substances, except glass or plastic, to improve the gemstones appearance.

R Irradiation

The use of neutrons, gamma rays or beta particles (high energy electrons) to alter a gemstones color. The irradiation may be followed by a heating process.

U Diffusion

The use of chemicals in conjunction with high temperatures to produce artificial color and/or asterism-producing inclusions.

W Waxing/Oiling

The impregnation of a colorless wax, paraffin, and oil in porous opaque or translucent gemstones to improve appearance.


Pearl Facts

Because of the rarity of naturally occurring pearls, a process of cultivating pearls was introduced in the early 1900s. In this process, a small bead of polished shell is inserted into an oyster or mollusk to act as an irritant and produce a pearl, which can take up to 24 months. These pearls are referred to as cultured pearls. Pearls are classically elegant and never go out of style.

Types of Pearls

  • Akoya: These pearls were the first type of pearl to be cultured. Japan and China are the main producers of these pearls. They are consistently round, which makes them perfect for strands. Colors range from white to cream, though some can be gray or black.
  • Freshwater: The freshwater pearl is usually slightly less round, smaller in size, and possesses less luster than other varieties of saltwater pearls. These pearls are usually cultivated in China and provide a value-priced option.
  • Mabé-(MAH bay): Instead of growing inside an oyster or mollusk like other pearls, the mabé pearl actually grows against the shell of the oyster, creating a dome-shaped pearl. This pearl is harvested, then assembled. The nucleus is removed and replaced by resin, while mother-of-pearl is used to cover the flat back. Mabés traditionally have high luster and lower prices than round pearls.
  • South Sea: These pearls are cultured in the northern waters of Australia, Indonesia, and the Philippines. These pearls are considerably larger than Akoya pearls and much more sensitive during the cultivation process. South Sea pearls are naturally white, cream, or golden in color.
  • Tahitian: These pearls are slightly smaller than the South Sea pearl, but are also sensitive during the cultivation process. The colors of black, silver, and gray occur naturally and they are cultured in Tahiti as their name implies.

Color

Pearls are produced in a variety of colors, as noted in the types of pearls. Most range from white, cream, and yellow to pink, silver, and black. Most pearls will have both a primary color, the first color you will notice, and a secondary color, the overtone you notice when you take a closer look. Color variation does not decrease the value of the pearl, but is important when matching pearls to be used in strands, earrings, bracelets, etc.

Luster

A pearl's luster is the result of multiple layers, also called the nacre (NAY ker), that the oyster or mollusk secreted to make the pearl. The thicker the nacre, the more luster a pearl has. You will notice the luster as the deep sheen that reflects light on the surface of the pearl.

Shape

Pearls come in a variety of different shapes. The most coveted of these is round. Akoya, Tahitian, and South Sea pearls are most often the roundest of the pearls. Other shapes can make beautiful jewelry as well, sometimes providing you with different price options.

Surface

Because pearls rely on an uncontrollable environment in which to grow, very rarely will you find a perfect pearl. The surface of a pearl may not always be smooth, often including spots, bumps, etc. The beauty of these pearls may be enhanced by the ability to sometimes be camouflaged during the stringing and setting process.

Size

The size of the oyster or mollusk that a pearl is produced within will have a direct effect on the size of the pearl. The size alone may not greatly impact the price of a pearl, but when you combine it with a perfectly round shape and beautiful luster, the value will dramatically increase.

Ring Sizing

We offer custom ring sizing at no additional charge. Most of our rings can be sized, but due to the nature of some designs, not all rings can be sized. When placing your order, an asterisk (*) beside a ring size option lets you know that your ring will be custom sized. Size options without the asterisk are stock sizes. Most custom sized ring orders leave our facility in as little as two business days. Use our convenient Ring Sizer to determine your ring size. Custom sized rings are not accepted for return.

Download and Print the Ring Sizer (PDF document)


Ring Sizer Instructions

In order to determine your ring size, we ask you to use the two different ways shown in the document. You may use just one, but we recommend using both in order to cross check the results and minimize the possibility of making a mistake.

First, using the sizer strip you have cut out, place it around the finger on which you wish to wear your ring. Make the numbers face outward and pull the sizer through the slit over the largest part of your finger (possibly your knuckle).

Be sure to pull it tightly for a more accurate sizing. Look at the slit and write down the number that lines up with it.

Second, use your own ring that fits the finger on which you wish to wear your new ring. Place the ring onto the circular sizers. Whichever circle your ring fits most closely with will be your ring size. If it falls in between sizes, go with the larger one.

The number results for both should match. If they do not, we suggest that you use the larger one to insure that you will be able to wear it when you receive it. Please note that your fingers will always measure smallest when it is cold, so you will not want to measure when they are cold.

We offer custom ring sizing at no additional charge. Most of our rings can be sized, but due to the nature of some designs, not all rings can be sized. When placing your order, an asterisk (*) beside a ring size option lets you know that your ring will be custom sized. Size options without the asterisk are stock sizes. Most custom sized ring orders leave our facility in as little as two business days. Use our convenient Ring Sizer to determine your ring size. Custom sized rings are not accepted for return.