Post by 1dave on Nov 22, 2020 16:28:20 GMT -7
www.yourgemologist.com/Kitchen/kitchen.html
A brief introduction:
www.gia.edu/gem-synthetic
A brief introduction:
We are standing in an ordinary kitchen inside an ordinary house. The cabinets are stocked with an ordinary array of food stuffs, condiments, and garnishes. The cabinets are also stocked with ordinary pots, pans, dishes, flatware, and serving utensils. In other words...we are in just about any kitchen, in any home, around the world. With one exception: along with us we have a high heat, high pressure hydraulic press. And with this press we are going to take ordinary items from this ordinary kitchen and make some extraordinary gemstones and minerals.
To do this we will take elements contained in these various items in this kitchen, mix them together in our hydraulic press, heat them to the required temperature, and allow them to form crystals of the various minerals that we choose to make. Admittedly we are taking some poetic license since the correct conditions of heat and pressure could not really be duplicated in our kitchen press, and some crystallization processes take millions of years. But for the sake of our understanding of gems and minerals, we will speed up time, turn up the heat, and increase the pressure enough to make this happen for us here in our ordinary kitchen, in our ordinary home, and within a short period of time
To do this we will take elements contained in these various items in this kitchen, mix them together in our hydraulic press, heat them to the required temperature, and allow them to form crystals of the various minerals that we choose to make. Admittedly we are taking some poetic license since the correct conditions of heat and pressure could not really be duplicated in our kitchen press, and some crystallization processes take millions of years. But for the sake of our understanding of gems and minerals, we will speed up time, turn up the heat, and increase the pressure enough to make this happen for us here in our ordinary kitchen, in our ordinary home, and within a short period of time
www.gia.edu/gem-synthetic
An Introduction to Synthetic Gem Materials
Robert Weldon
Synthetic Emeralds
Jump To:
Flame Fusion or Verneuil process (melt process)
Crystal Pulling or Czochralski process (melt process)
Flux growth (solution process)
Hydrothermal growth (solution process)
Synthetic diamond (this is not frequently encountered)
Synthetic corundum (widely available)
Synthetic emerald (widely available) and other beryls (rare)
Synthetic quartzes (widely available)
Synthetic Spinel (widely available)
Synthetic Opal (occasionally seen)
Synthetic Alexandrite (rare)
A synthetic gem material is one that is made in a laboratory, but which shares virtually all chemical, optical, and physical characteristics of its natural mineral counterpart, though in some cases, namely synthetic turquoise and synthetic opal, additional compounds can be present.
Synthetic gem crystals have been manufactured since the late 1800s, and their production is often marked by a need for them in industrial applications outside of the jewelry industry. The first success was in producing synthetic ruby of faceting quality. Synthetic crystals are used in communications and laser technology, microelectronics, and abrasives. Because synthetics for jewelry applications can be “made to order” [i.e. consistent color and crystal shape] given the right ingredients, time, and the facilities to grow them, they are likely to be much less rare than natural gems of equal size, clarity, and saturation of color. Because of this, and because it is possible to confuse them with gems that are naturally occurring, there are strict guidelines regarding how they are marketed and sold.
In the United States, the Federal Trade Commission requires that any gem material produced in a laboratory be described in a way that leaves no doubt that it was not produced naturally. It is considered to be a deceptive practice if a synthetic gem material’s origin is not clearly disclosed throughout the distribution channel at the time of sale, from the manufacturer to the consumer. There are also a number of industry organizations such as the American Gem Trade Association (AGTA), the International Colored Gemstone Association (ICA), and the World Jewellery Confederation (CIBJO) that have formulated specific guidelines for their members regarding the disclosure of synthetic gems at the time of sale. In the last decade fewer new kinds of man-made gem materials have been marketed. This suggests that the repertoire of synthetic gem materials is close to reaching its limit in terms of the creation of new materials, but it is not limited in production which is still very significant. During the last century, researchers have developed a number of different ways to create these synthetic gem materials in the laboratory. Most of these methods fall into two major categories – melt or solution.
In melt processes, the chemical composition of melt is the same as the composition of the resulting crystal. In solution processes, the solution or melt has a different chemical composition than that of the resulting crystal. Constituents are dissolved in the solution or melt at high temperature, and the crystal forms initially on a seed crystal as the melt temperature is lowered. Some of the main synthetic processes include:
Flame Fusion or Verneuil process (melt process)
The first commercially successful synthetic gems were created by the flame fusion process. This process involves dropping powdered chemicals through a high-temperature flame, where it melts and falls onto a rotating pedestal to produce a synthetic crystal. Today it remains the least expensive and most common way to make gems such as synthetic corundum and spinel.
Robert Weldon
Synthetic Emeralds
Jump To:
Flame Fusion or Verneuil process (melt process)
Crystal Pulling or Czochralski process (melt process)
Flux growth (solution process)
Hydrothermal growth (solution process)
Synthetic diamond (this is not frequently encountered)
Synthetic corundum (widely available)
Synthetic emerald (widely available) and other beryls (rare)
Synthetic quartzes (widely available)
Synthetic Spinel (widely available)
Synthetic Opal (occasionally seen)
Synthetic Alexandrite (rare)
A synthetic gem material is one that is made in a laboratory, but which shares virtually all chemical, optical, and physical characteristics of its natural mineral counterpart, though in some cases, namely synthetic turquoise and synthetic opal, additional compounds can be present.
Synthetic gem crystals have been manufactured since the late 1800s, and their production is often marked by a need for them in industrial applications outside of the jewelry industry. The first success was in producing synthetic ruby of faceting quality. Synthetic crystals are used in communications and laser technology, microelectronics, and abrasives. Because synthetics for jewelry applications can be “made to order” [i.e. consistent color and crystal shape] given the right ingredients, time, and the facilities to grow them, they are likely to be much less rare than natural gems of equal size, clarity, and saturation of color. Because of this, and because it is possible to confuse them with gems that are naturally occurring, there are strict guidelines regarding how they are marketed and sold.
In the United States, the Federal Trade Commission requires that any gem material produced in a laboratory be described in a way that leaves no doubt that it was not produced naturally. It is considered to be a deceptive practice if a synthetic gem material’s origin is not clearly disclosed throughout the distribution channel at the time of sale, from the manufacturer to the consumer. There are also a number of industry organizations such as the American Gem Trade Association (AGTA), the International Colored Gemstone Association (ICA), and the World Jewellery Confederation (CIBJO) that have formulated specific guidelines for their members regarding the disclosure of synthetic gems at the time of sale. In the last decade fewer new kinds of man-made gem materials have been marketed. This suggests that the repertoire of synthetic gem materials is close to reaching its limit in terms of the creation of new materials, but it is not limited in production which is still very significant. During the last century, researchers have developed a number of different ways to create these synthetic gem materials in the laboratory. Most of these methods fall into two major categories – melt or solution.
In melt processes, the chemical composition of melt is the same as the composition of the resulting crystal. In solution processes, the solution or melt has a different chemical composition than that of the resulting crystal. Constituents are dissolved in the solution or melt at high temperature, and the crystal forms initially on a seed crystal as the melt temperature is lowered. Some of the main synthetic processes include:
Flame Fusion or Verneuil process (melt process)
The first commercially successful synthetic gems were created by the flame fusion process. This process involves dropping powdered chemicals through a high-temperature flame, where it melts and falls onto a rotating pedestal to produce a synthetic crystal. Today it remains the least expensive and most common way to make gems such as synthetic corundum and spinel.