While not as widespread or prized as the blue one, yellow sapphire is a wonderful precious gem that can be a beautiful addition to your jewelry collection. This stone also has a special significance for Hindus or Vedic astrology. Regardless of why you choose a yellow sapphire, you still need to know how to check it to make sure it is authentic, natural and relatively perfect before buying it.
Steps
Method 1 of 3: Recognizing the Fake
Step 1. Compare the yellow sapphire with a piece of yellow glass
Most fakes are made of glass. Although at a glance the yellow glass could be similar to sapphire, the two are decidedly different from each other. In general, yellow glass is too large and too colored to be true.
Step 2. Look for bubbles
Sapphires can have various imperfections inside, but the high quality yellow ones do not have these inclusions visible to the naked eye. Fake ones, on the other hand, often have small bubbles inside.
Step 3. Check for scratches
Sapphire, of any color, is extremely hard. Diamond is by far the hardest gem, and has a value of 10 on the Mohs scale for the hardness of the minerals, sapphire is 9.0 on the same scale. As such, very few materials can scratch it. The glass, on the other hand, is placed between 5.5 and 6.0, and is much easier to scratch. A thick glass imitation has many surface scratches, while real sapphire has very few, if any.
Step 4. Note the facets
Since glass is not as hard as sapphire, it is much easier to cut. Yellow glass stones are cut very simply and usually have smooth, rounded edges. Instead, yellow sapphires have more complex cuts that are precise and sharp.
Method 2 of 3: Recognizing the Synthetics
Step 1. Make a note of the cut
On a small scale, natural yellow sapphires can be cut into almost any style. When the stones are larger than a carat, however, many jewelers tend to prefer the oval or cushion mixed cut. Since round and emerald cuts are more popular, however, jewelers often cut the synthetic stones into round and emerald shapes. Natural sapphires, in theory, can be cut into the same shapes, but it is much less likely.
Step 2. Be wary of "X" cuts
Manufacturers of synthetic stones often make an "X" cut, also called a scissor cut, on the facets of the stone.
Step 3. Avoid the "grooves"
Sometimes the facets of synthetic stones are not as sharp as those of a natural sapphire. This flaw looks very similar to the grooves you can expect on a vinyl record, but can usually only be seen under a 10x magnifying glass.
Step 4. Check the stone under the magnification
A good synthetic can have flaws that are only visible at 10x or 30x magnifications. Under a 10x you can usually spot the curve and grooved stripes found in synthetic sapphires, especially when the examiner places a piece of clear glass between the stone and the light source. A higher magnification such as a 30x is able to identify gas bubbles and masses of dust that have not melted.
Method 3 of 3: Recognizing Other Frauds
Step 1. Pay attention to the fills
Like any stone, yellow sapphire occasionally contains inclusions and empty spaces within it. When a gem cut involves one of these imperfections, a small hole can develop. Most jewelers prefer to keep the hole in the gem rather than cut it, but some unreliable jewelers sometimes fill the stone with glass or borax paste to add weight and make the stone look of better quality. Examine the stone against the light using a glowing lamp. Irregular patches are usually a good indication of this practice.
Step 2. Be aware of the foils on the stone
The protective foil reflects more light, making the yellow sapphire color more vibrant and lustrous. The backing can be difficult to see if the stone is already mounted on a piece of jewelry, but careful examination of the stone's base under magnification can often reveal the film. Additionally, this potential forgery is more commonly found in antique jewelry, meaning you don't have to worry too much if you've bought a new piece.
Step 3. Keep in mind the assembly
If you are unsure about which vendor you plan to buy the stone from, consider buying unassembled or mounted stones so that you can check the underside of them. Claw, tension or gallery setting are good examples. On the other hand, closed montages, such as the bezel one, are often used by scammers to hide defects and evidence of willful misconduct.
Step 4. Observe the color
True yellow sapphire is a pure but uniform yellow, while less valuable imitations often have slightly different shades. Citrine has a slight green tint, golden topaz has strong traces of orange, and yellow tourmaline has a bright hue, similar to the color of lemon.
Step 5. Ask for certification
Although the certificate does not give you the same guarantee as the physical control of the stone, it offers you the satisfaction of knowing that the stone has been checked and approved by a trusted official or organization. Look for the certificate issued by qualified national companies.
