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First, it should be said that “opal” is a geological term, while “opalite” is a pure trade name. This trade name was invented to increase the attractiveness of this material to buyers because it is similar to the name of the opal gemstone. So are opalite and opal the same thing?
Opal and opalite are fundamentally different substances with almost identical appearances. Even though the structure of opal and opalite will be similar, these substances will completely differ in their physical and chemical properties and chemical composition.
In this article, you will learn what opalite is called and why opalite cannot be called opal. We will also explain the differences between opal and opalite and how to distinguish these two substances apart.
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Are Opal and Opalite the Same?
Therefore, we can state that in the modern world, the terms “opal” and “opalite” denote entirely different substances. Opal is a natural substance that formed over centuries in natural conditions without human intervention.
According to its chemical formula, opal is a silicate with many water molecules in its composition in a bound form SiO2*H2O. Opalite, on the other hand, is a trading term for a material that is entirely man-made and has a completely different chemical composition.
For example, glass, although a silicate, does not contain any water in its composition, and the opalescent effect is achieved through various chemical additives that are absent in opal. Epoxy resins and polymers are entirely organic substances. Opalite is used as an imitation of opal in cheap jewelry.
Opalite – is a trading name for artificial imitations of opal. Various materials are used to imitate opal, ranging from different polymers and epoxy resins to glass and even an unusual modern material such as nanosital (an artificial material between glass and mineral in its chemical composition).
The primary condition is that this imitation should have an opalescence effect (a unique play of colors that occurs in opals). Such an imitation under the name “opalite” was first noticed at the Gem and Lapidary Dealers Association (GLDA) Tucson show in February 1988.
The well-known gemological laboratory GIA conducted a series of studies on this substance and found that it is plastic with a unique internal structure, which gives the opalescence effect.
This effect is produced by the close-packed structure assumed by the minute (150-300 nm) polystyrene spheres during the slow sedimentation process by which the material is formed in the laboratory.
Because of the realistic play-of-color, these imitations cannot be separated conclusively from either natural or synthetic opals based on unaided visual observation alone.
At that time, such plastic had been produced in Japan since 1978. However, today, under the trade name “opalite,” can be any material that has an «opal appearance».
Further study of this issue revealed that the term “opalite” existed long before 1988 and was referred to as a natural substance. Indeed, the term “opalite” can be found in American geological dictionaries from the 1940s.
According to the definitions from these dictionaries, opalite is a natural opal that does not have an opalescence effect. This term was successfully used worldwide until opalite began to refer to artificial opal imitations in the 1980s.
Therefore, confusion can arise when someone refers to a natural opal without the play of colors as opalite due to the term’s current usage.
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Is Opalite Fake Opal?
Opalite is not a fake opal until it is presented as natural opal. However, this statement is true for any imitation of opal. As we have already established, opal and opalite are absolutely different materials with similar appearances. Because of this, it can be used as a fake.
Dishonest dealers can take advantage of this by selling opalite as opal. In this case, opalite can be considered a fake opal.
Of course, the price of opalite is hundreds and thousands of times lower than that of natural opal. Suppose a seller sells imitation opal under the name opal. In that case, he must explain to customers that it is not natural opal.
TIP: Opal is a one-of-a-kind, precious gemstone. Find out the key factors that determine opal’s value in the article below:
8 Factors Why Opal is Valuable (Prices for Different Types)
How to Tell Opal from Opalite?
Opal and opalite have entirely different physical and chemical properties. How difficult it is to distinguish opalite from opal depends on the material used to create the opalite, the person’s experience in identifying minerals, and the identification tools available.
To tell opal from opalite, you may focus on these main differences like play-of-color, hardness, specific gravity, and the microscopic pattern of the material. Real opal is harder; it has higher specific gravity than opalite, patches and flashes of color, and luck any microscopic honeycomb patterns.
Let’s look at a specific example when we need to identify opalite created from plastic. Separating a plastic imitation solely based on heft is a simple matter with loose stones.
The specific gravity of the plastic counterfeit is so radically different from that of either natural or synthetic opal that the plastic is immediately apparent, and no further testing is required. If the opalite is made of glass, it will be heavier than opal in most cases.
However, most sellers seldom sell opalite as loose stones. When these opal imitations are in jewelry, the “heft test” is useless.
In this respect, it is interesting that the earlier Japanese-produced material reported in the literature was only sold mounted in jewelry. In most cases, identifying these plastic imitations requires additional gemological testing.
There are destructive methods for identifying plastic opalite that gemologists rarely use, but they are extremely simple and do not require any equipment. In addition, such methods are most convenient to use in field conditions.
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Here is a step-by-step guideline for real opal and opalite differentiation:
- Step 1
The first method is determining the material’s melting temperature. To do this, take a needle, heat it on fire, and touch it to the sample. If it is plastic, it will melt under high temperatures and start emitting a characteristic “plastic” smell.
- Step 2
The second method is determining the hardness. The radical difference in hardness between a plastic imitation and a natural or synthetic opal makes hardness testing very useful. In this case, it can be done carefully (to avoid damaging the piece) in an inconspicuous place on the test subject.
With magnification, it can be observed that the fine point of an ordinary sewing needle will readily dent opalite when only the slightest pressure is exerted. Such a test will not dent gem-quality natural and synthetic opals.
However, some poor-quality, highly porous natural opals may be. But these two methods will not be effective if the opalite is made of glass or some strong modern material.
- Step 3
Other gemological methods require gemological tools and minimal knowledge of gemology. The most specific device is a gemological loupe. If you carefully examine the sample under 10-x magnification, you may notice some characteristics typical of artificial material.
For example, if the opal imitation is a doublet, you will see the bonding line under the loupe. An even better tool for such examination is a gemological microscope. It provides more powerful magnification of the object and allows for different types of lighting of the sample being studied.
For example, we will cite the examination of opalite under a microscope by GIA experts:
“…In examining any opal or opal-like material, oblique illumination can be used, together with shadowing and transmitted light, to show specific patches of color-play and how they relate to the overall structural appearance of the substance (Gubelin and Koivula, 1986). When studied in oblique surface incident light with a standard gemological microscope, the 2.63-ct oval showed a “pinfire” play-of-color pattern that could be easily mistaken for the play-of-color shown by some natural opal.
In shadowed transmitted light, the “pinfire” structure was transformed into the highly diagnostic so-called honeycomb or lizard-skin pattern always associated with laboratory-grown products exhibiting play-of-color. So, based on this structure, a gemologist would at least associate this cabochon with an artificial material generally, if not a plastic imitation specifically.”
- Step 4
Another method is the reaction to ultraviolet radiation. For this, it is desirable to have a gemological ultraviolet lamp. Still, an ultraviolet flashlight can also cope with this task.
The essence of the method is that polymer materials usually emit characteristic neon light under the influence of ultraviolet radiation.
However, when using this method, it should be remembered that some natural opals can also glow under ultraviolet light, and some artificial materials can be inert.
- Step 5
One of the most common methods for diagnosing gemstones is measuring the refractive index. This method requires some experience working with a refractometer and the availability of the refractometer itself.
Because natural opals have refractive indexes in the range of 1.37 to 1.47, R.I. is a helpful indicator in separating opalite from natural or synthetic opal, considering there is no interference from a mounting.
- Step 6
And, of course, we should not forget about the most complex, expensive, and reliable methods of diagnosing opal. Specialists in modern gemological laboratories use such methods. For example, these are the Infrared Spectroscopy and LA-ICP-MS methods.
TIP: Many different fakes have been created to make opal affordable to a broader range of people. Check out the main differences between real and fake opals in the article below:
Real vs. Fake Opal: Focus on These 6 Differences
Differences between Opal and Opalite
Opalite can be made from any material with a characteristic play of colors, making it similar to natural opal. Of course, depending on the material, the physical and chemical properties of opalite will be different.
But despite this, it will never have all those physical features and properties natural opal has. Opalite usually differs from opal in its weight, hardness, and magnified appearance.
Let’s consider an example when opalite is made of polymer – the most common case. Opal data in this table is taken from https://www.gia.edu/opal.
|Properties||Opal||Opalite – opals’ plastic imitation|
|Visual appearance||Opalescence||Realistic play-of-color|
|Appearance under magnification||It does not have the honeycomb or lizard-skin pattern||It can have a so-called honeycomb or lizard-skin pattern. Glass can have glass-like bubbles inside|
|Specific Gravity (SG), g/sm3||1.98-2.25||0.8-1.40|
|Heat sensitivity||If touched with a hot needle, the point of contact may crack, but melting will not occur||When heated, it melts and emits a characteristic unpleasant smell|
|Hardness (Mohs’ scale)||5-6.5||2-3|
|Refractive Index (RI)||1.37-1.47||1.30-1.70|
TIP: Correctly cutting and polishing opals brings beauty and exceptional color flash. Find out the step-by-step guide on how to cut and polish opals in the article below:
How to Cut & Polish Opals: Follow These 9 Simple Steps
So, in summary, opal and opalite are two different substances. Opal is a natural gemstone, while opalite is an artificial material that imitates the appearance of opal. If you have a sample that looks like an opal, you can:
- Compare the weight of the sample to the weight of a real opal – the weight of plastic opalite will be noticeably lower. You can also measure the density of the sample and compare it to reference data.
- Check the hardness of the sample – plastic opalite will easily scratch with a regular needle.
- Check if the sample’s surface melts when touched with a heated needle and if a characteristic odor is emitted.
- Carefully examine the sample under a gemological loupe or microscope – plastic can have a honeycomb or lizard-skin pattern, and glass can have glass-like bubbles inside. Also, if the sample is a doublet, you can spot the place where the parts of this sample are glued together.
- Check the refractive index and compare it to reference data.
- Subject the sample to ultraviolet radiation – this can check the fluorescence of the sample, as well as, under this type of light, better examine the sample for the presence of glue (if the sample is a doublet or triplet) and for the presence of internal defects characteristic of glass.
If you still can’t determine the exact material after all these manipulations, seeking help in a gemological laboratory is better.
TIP: Opals aren’t found in all U.S. states, but they are commonly found in Nevada. Check out the best locations in the United States in the article below:
4 Best Locations for Finding Opals Near Me (United States)