How big to buy?
For many women, a gemstone’s size should be determined by her hand.
Some people believe that the bigger the size, the better the gemstone. The size you purchase should be a factor not only of your budget, but also of the preferences of your fiancé.
The other Cs - Clarity, Color and Cut - also influence a gemstone’s price. A large stone looks out of place on a petite hand, whereas a tiny stone may be lost or insignificant on a larger finger.
The stone’s shape should also be proportioned to the hand, which may allow a smaller carat weight to look lovelier than a large stone with an improper shape.
Which Clarity Should I Purchase?
Gemstone clarity is critical for engagement rings; most stones have various types of flaws.
Inclusions are additional minerals that may cause a streak or stripe through the stone, and fractures are miniscule cracks and splits that look like tiny crystals, clouds or feathers. Clarity is the scale of perfection established by the Gemological Institute of America (GIA) that measures the number and magnitude of flaws in a diamond.
Gemstones are graded for clarity under 10x loupe magnification. Grades range from Internally Flawless gems that are completely free of blemishes to Imperfect 3 gems that possess large, heavy defects visible to the naked eye; we don’t sell or trade with I-3 gemstones.
The most common clarity grading are VS2, SI1 and SI2. These stones are in the middle of the scale for flaws - not totally flawless and yet not having lot of flaws. That makes them affordable for many, and depending on the cut and setting of the stone, many of the flaws may not be noticeable.
Which Gemstone Should I Purchase?
Buying an Emerald:
When judging an Emerald’s value, its color is of paramount importance, the more vivid the green, the more valuable the stone.
There are also attractive lighter green Emerald that are lively and vivid when set in Emerald Jewelry and darker green gems that make up in rich green color what they lose in brightness. Generally speaking, however, very light or dark Emeralds are less expensive.
Unlike a Diamond, a finely colored Emerald is not significantly devalued by inclusions, the fewer fissures the more expensive the Emerald. Natural Emeralds of top quality weighing more than two carats are extremely rare and costly. A large deep green Emerald with minor blue or yellow secondary coloration that is relatively free of inclusions may cost tens of thousands per dollars per carat. Perfect natural gems in color and appearance are very rare and expensive. As part of the normal fashioning process, most Emeralds are immersed in clear oil or resin to minimize the appearance of small fissures. In addition to oil and wax fillers, the trade also uses clear resins to penetrate open fissures surfacing in the gemstone. Hardeners are often added to solidify these liquids to prevent the resin from evaporating, thus making the enhancement more permanent than just oiling or waxing the gem.
Be sure to buy from a reputable dealer who will provide, in writing, the processes and treatment that your Emerald has received. Because Emerald are brittle, and can split along their inclusions if exposed to sharp impact, properly designed Emerald jewelry should minimize the gem's exposure, especially in rings and bracelets.
Buying a Ruby:
Color is of paramount importance when judging the value of a Ruby. Prized colors which can command high prices are pure reds with no overtones of brown or blue. Very light or dark shades are usually less valuable, but not necessarily less appealing. Beauty is in the eye of the beholder and color preferences are subjective.
Of course, clarity, cut and carat weight factor into the cost of a gem.
Better quality Ruby Rubies are usually eye-clean with some inclusions under magnification. Ruby is more available under two carats, gems over five carats have become scarce. In Ruby’s finest quality, any size is rare.
Don't let yourself become overly concerned about the origin of the gem.
A gem from Burma may not necessarily be better than a gem from Vietnam.
If the Ruby has a color that appeals to you, and a clarity that looks good, then that is more important than its nationality. However, it is important to buy from a reputable dealer who will provide written documentation about the Ruby’s size, and any treatments it has undergone.
Recently, Ruby Rubies have been grown in the laboratory. Although these grown rubies are essentially of identical composition, hardness, and brilliance to natural Ruby Rubies, they have aroused some controversy. Their presence of the market is still more limited than lab-grown emeralds. However, when buying star rubies, look for a star that has straight legs that are all of equal clarity.
Buying a Sapphire:
Color is of paramount importance when judging the value of Sapphire. The purer the blue of a natural Sapphire, the greater the price the gemstone can command. Gems that are too dark or too pale are usually less valuable, but not necessarily less appealing. Beauty is in the eye of the beholder and color preferences are subjective.
In recent years technology has perfected the process of heat-treating sapphires exposing them to very high temperatures to eliminate impurities. In fact most Sapphires on the market today have been heat-treated to improve clarity and color. This process is stable and does not affect the value of the gem, except at the highest level of the market. Occasionally, colorless to pale blue sapphire is diffusion treated.