More ways to distinguish red sapphires

How to distinguish red sapphire jewelry

Case: Ms. Xu is an executive of a foreign trade company in Beijing. She is also a full-fledged jeweler. Not only does she have a jewel in her own life, but she also has a wide variety of jewellery, especially red and sapphire. . However, Ms. Xu told reporters that there are very few treasures in her family that are “famous”. This makes her very upset because she likes gems very much. Every time she goes to the jewels, she is always fooled. Therefore, she would like to ask the experts to teach a few basic tricks to distinguish red and sapphire.

Guidance expert: Professor Yu Xiaojin, senior expert of China Geological Museum

What is red, sapphire

Ruby and sapphire are commonly referred to as red and blue gems. In fact, real rubies and sapphire are gem-quality corundums (corundum is a mineral name). The hardness of red and sapphire is The minerals of nature are second only to diamonds. Their chemical composition is alumina (Al2O3). It is colorless when pure. It is red when it contains 0.9%-4% of chromium. It is blue when it contains iron and titanium. The shape is three-way. Crystalline, the crystal form in nature is often columnar (slightly thin at both ends, slightly thick in the middle) or plate-shaped hexagon, the appearance is more like barrel; color is mainly colorless, red and blue, ruby ​​is mainly deep Fuchsia or orange-red, sapphire is mainly blue or blue-green, and other colors are green, yellow, pink, brown, etc.; hardness is 9; relative density is 3.99-4.0; due to common polycrystalline twin crystal, contact twin crystal, There will be cracking; the whole is transparent to translucent, the gloss shows glass luster to the aramid luster, the ruby ​​has obvious red fluorescence under the ultraviolet lamp, and the sapphire mostly has no fluorescence; usually the red and sapphire have a refractive index of 1.762- 1.7 78. For red and sapphire containing three sets of aligned fibrous inclusions, a curved surface cut can be used to produce a starlight effect.

Red, sapphire value measurement

The value of red and sapphire is closely related to its particle size and weight. Gems below half a carat are more common and cheaper; if more than one carat is much more expensive, more than 3 carats will rise in geometric progression. If it is more than 10 carats and the quality is very good, it is very rare, worth up to several million dollars.

Generally, the following levels can be divided to estimate the value:

Below 0.5 carat, fine grain, easy to get, is very cheap for group setting;

0.5-1 carat, small grain, easy to get, can be used as a small ring face, cheap;

1-2 carats, medium grain, generally affordable, can be used as a ring pendant;

2-3 carats, larger grain, higher value, large market demand;

3-5 carats, large grain, high value, rare;

More than 5 carats, very large, expensive, very rare.

The difference between red and sapphire natural products and synthetic products

The red and sapphire natural products and synthetic products are very different in appearance. First, the growth lines in the gemstones are observed. The flame melting method is mostly curved, while the natural crystals form straight fold lines. Again, observing the inclusions in the gemstone, the flux method synthetic gemstone often contains the melting point of the melting point and the coloring flux residue, which is a "worm-like" under a 20-fold magnifying glass; sometimes there are circular bubbles and Tiny bubbles, sometimes visible hexagonal or triangular platinum pieces that fall off the enamel. The inclusions in natural gemstones are mostly fine rutile crystals or fingerprint-like gas-liquid inclusions; small cracks are also common. The last thing is to observe its color. The color of the synthetic product is too bright and very uniform. It looks a bit dull and glaring, while the natural color is relatively soft.

Cutting is also an important factor affecting value

Red and sapphire are also very particular in cutting, including faceted and plain noodles; the shape is elliptical, round, emerald, pear, olive and mixed. The most popular one is the hybrid shape, which is a wide oval shape. The evaluation of the cut is not as strict as the diamond, and generally does not account for a large part of the value of the gemstone, but if the cut is too bad, it greatly affects its value.

Good cuts pay attention to three points: 1. Cut positioning: Because red and sapphire are anisotropic, they have pleochroism. When cutting, the table should be strictly perpendicular to the long axis, avoiding the influence of pleochroism, so that the finished product can see the purest and saturated color from the table, which is the correct orientation. Otherwise, it will cause color misregistration and be motley due to pleochroism. 2. Proportion and symmetry: Regardless of the type of cutting used by the gemstone, it must meet the requirements of the standard specification, and the symmetry is better and cannot be skewed. The ratios and angles of length, width and thickness are important and must be met in accordance with the standards, because these standards are designed according to the refractive index of the gemstone and the principle of total reflection of light, which can achieve the effect. If it is thin, it will leak light, the color is light, and the dispersion effect is also poor. In the jargon, there is no "fire head", which is called "fisheye effect". It looks dull and brilliance. If it is cut too thick, it will change color. Dark, also affects the "fire head." 3. Polishing degree: the quality of polishing will affect the luster of the gem. High-quality polishing gives the gem a stronger glow and shines. 4. Starlight effect: For red and sapphire containing three sets of aligned fibrous inclusions, a curved surface cut can produce a starlight effect. The cutting of such gemstones must not only consider the symmetry and proportion, but also select the direction and position so that the starlight of the finished product is in the middle. If the cutting is not good, the value will be reduced if it is skewed.

Single Jersey

Single Jersey,Single Jersey Supima Cotton Fabric,Single Jersey Knitted Fabric,Single Jersey Printed Fabric

Shaoxing Huangdaopo Trade Co.,Ltd. , https://www.sxhdptrading.com