There are more than 3000 kinds of minerals in nature, and only 240 kinds can be used as gems, which shows that gems are the essence of many mineral rocks.
So what kind of minerals or rocks can appear in jewelry design?
Color, light color, transparency, dispersion (flicker or not), special optical effects (such as moonstone, opal, opal)
2. Persistence
Hardness, toughness and stability (thermal stability and light stability)
scarce
Raw stone selected after diamond mining.
Rare things are the most valuable diamonds: only 250 tons of ore can produce 1ct diamonds (total weight, not necessarily big diamonds).
Ordinary emerald ore
Emerald: Rare quality-high quality emeralds are very rare in production.
Amethyst original stone
Beautiful amethyst is cheap because of too much output.
We are often asked how to maintain jewelry.
Then the question is, under what circumstances will the gem be damaged?
When external forces intervene, such as friction, bumping and scratching.
We often see news such as jade fracture, but we have hardly heard of Hetian jade fracture. Why?
Jadeite (jadeite) and nephrite (hetian jade) are both chain silicate structures, and their Mohs hardness is about 6.5 (generally jadeite is slightly harder than hetian jade), but hetian jade is tougher than jadeite because of its slightly different chain structure. Yes, in addition to hardness, the basic physical properties of gemstones include cleavage, cleavage, toughness and other mechanical properties.
We often say that diamond is the hardest substance in the world. The hardness here refers to the ability of an object to resist mechanical effects such as scratching, pressing or grinding by external forces.
Repair the broken jade bracelet
If the jade bracelet is broken, we will say that it is safe all the year round (poor toughness). The toughness here is also called strike hardness, and the hard-to-break property is toughness;
Emerald has high hardness and brittleness, and brittleness is the brittle property.
Ruby multifractal
The cleavage of rubies is something that we should pay great attention to when designing mosaics.
So there is a reason why diamonds with stable physical properties are actually the most worry-free gems when making jewelry.
Octahedral rough diamond
Diamond, the king of jewelry, as the most famous jewelry, is closely related to its own characteristics.
As a representative of equiaxed crystal system, diamonds give people the conventional impression that they are shiny, transparent and hard.
These all come from its physical properties, and the luster comes from the diamond luster and high dispersion of diamonds.
The crystal morphology of the original stone is closely related to its internal structure.
The hardness is due to the octahedral valence bond structure of C atom in diamond.
The formation of natural colored diamonds comes from lattice defects and color centers during diamond growth.
The price of diamonds (white diamonds) is mainly determined by 4C.
That is, people often say size, clarity and color cutting.
The 4c grading method of diamonds has great reference value for the grading of colored gemstones.
Since ancient times, only the bright ruby has won the title of "king of jewelry".
Dove blood red is the most precious ruby.
In fact, top rubies with larger particles are more rare and precious than diamonds. At present, the average price of 1ct ruby on the market is 2000 USD /ct, and the price will increase geometrically if the quantity is large (applicable to all gems).
Warm red is mainly caused by a trace of Cr (0. 1~3%).
Its Mohs hardness is 9 and its wear resistance is very good. Ruby with strong glass luster and good polishing amount is very shiny.
Ruby's sister sapphire. That's too much.
Colorful sapphires of various colors.
According to GB/T 16552-20 17, all corundum gems except rubies, including blue, turquoise, green, yellow, orange, pink, purple, gray, black and colorless corundum, are collectively called sapphires.
The colors of blue sapphires are also varied, and it can be seen that some sapphires have strong purple tones.
It can be seen that the classification of colors in different laboratories is very different.
The two most expensive colors are cornflower and royal blue.
Cornflower sapphire
Cornflower: A deep blue with a hazy purple hue, giving a velvety appearance and a slightly opaque sapphire.
Sapphire
Sapphire: a kind of sapphire with pure color, clarity and high saturation.
But for people like me who are not sensitive to color, in a word, sapphire is bluer and darker than cornflower.
Mohs hardness 9, strong glass luster to sub-diamond luster (theoretically, sapphire should be brighter than ruby, but the brightness looks similar because of the cold color)
star ruby
Starlight sapphire
Ruby and sapphire belong to the three-in-one corundum family and can have starlight effect.
The reason is that the growth of corundum is often accompanied by rutile, so that there are three-dimensional rutile inclusions corresponding to its symmetry axis.
Rutile inclusions in rubies
Among the five kinds of gemstones, not only rubies and sapphires, but also emeralds with hexagonal system have the characteristics of producing starlight effect.
Xingguang emerald
Emerald is also a gem colored by Cr. Because of its different internal structure, Cr3+ gives it soft and bright colors, and it has a velvet texture, just like a green lawn. Its high-quality bright color without oil is more valuable than the same grade of diamond (colorless). (Colombian oil-free emerald, the price can be as high as10-150,000 /ct)
The emerald interior is also called the garden of cracks and inclusions.
Emerald is naturally cracked, with a hardness of 7.5-8 and high brittleness, so great attention should be paid to avoid colliding with other high-hardness gems when designing and inlaying.
The color of colored gems determines its value, with rich and bright colors as the best, and those that are neither deep nor shallow as the best.
Muzo emerald
It is generally believed that the best emeralds come from the famous Muzo mining area in Colombia.
The above are four kinds of gems commonly used as main stones in design, among which the special starlight effect mentioned and the golden emerald among the five gems will be described in the next chapter on several special optical effects of gems.