Amorphous Diamond Treatment
Our Asha diamond simulant has been examined by four different independent testing laboratories to show the results of the amorphous diamond infusion process.

The tests performed include:
  1. X-Ray Photoelectron Spectroscopy (XPS)
  2. Raman microspectroscopy
  3. Contact Angle Goniometry
  4. Review by International School of Gemology
XRay Photoelectron Spectroscopy
Purpose: To verify the elemental (surface) composition of the Asha Diamond Simulant
Results: "The principal element found at the surface is carbon".

What is X-Ray Photoelectron Spectroscopy (XPS)?
X-ray Photoelectron Spectroscopy (XPS) is a quantitative spectroscopic technique that measures the empirical formula, chemical state and electronic state of the elements that exist within a material. XPS spectra are obtained by irradiating a material with a beam of X-rays while simultaneously measuring the kinetic energy (KE) and number of electrons that escape from the top 1 to 10 nm of the material being analyzed. XPS is used to measure elemental composition of the surface (1-10 nm usually).
Source: Wikipedia

The principal element found at the surface is carbon. As would be expected, considerable surface oxygen was also measured.

An atomic concentration of zirconium of 3.1 atomic % was found in the surface of the coating [note: they indicated that during the coating/infusion process, some of the zirconium is being knocked into the mix].

The elemental concentrations in atomic % of the surface of the DLC coated Asha diamond simulant after the removal of surface debris with ultrasonic cleaning are:

ElementsAsha Diamond Simulant Surface
C (Carbon)77.07%
O (Oxygen)17.09%
Zr (Zirconium)3.14%

At concentrations below 1 atomic % N(0.71%), Y(0.61%), Si(0.53%), F(0.42%), Cl(0.31%), and Mg(0.11%) were detected in the coating.

Test performed by: Anderson Materials Evaluation Laboratories (April, 2007)

Equipment used: "The surface of the coated Asha diamond simulant after ultrasonic cleaning was examined with XPS using a monochromatic aluminum X-ray source. The quantitative elemental concentration results were obtained from elemental survey spectra covering the binding energy range from 0 to 1100 eV with a step size of 0.5 eV and long 4 hour data acquisition time for improved accuracy".

Raman microspectroscopy
Purpose: To verify Asha contains diamond content
Results: The Asha shows a diamond signature when run under Raman.

What is Raman Microspectroscopy?

Technical explanation
Raman spectroscopy is a spectroscopic technique used in condensed matter physics and chemistry to study vibrational, rotational, and other low-frequency modes in a system. It relies on inelastic scattering, or Raman scattering of monochromatic light, usually from a laser in the visible, near infrared, or near ultraviolet range. The laser light interacts with phonons or other excitations in the system, resulting in the energy of the laser photons being shifted up or down. The shift in energy gives information about the phonon modes in the system. Infrared spectroscopy yields similar, but complementary information.

Typically, a sample is illuminated with a laser beam. Light from the illuminated spot is collected with a lens and sent through a monochromator. Wavelengths close to the laser line (due to elastic Rayleigh scattering) are filtered out and those in a certain spectral window away from the laser line are dispersed onto a detector.
Source: Wikipedia

What does this mean?
A laser light is shot into the sample. The laser photons interact with molecules in the sample, causing the photons energy to go up or down. This shift in energy is captured and measured. This creates a "fingerprint" (as stated above) through which the sample can be identified.

Therefore, the Asha spiked at the same point as the diamond because of the interaction of the laser photons with the carbon atoms. Since the amorphous diamond layer and the genuine diamond both are composed of SP3 carbon molecules, one would expect that the two samples would interact similarily at a single point with the laser photons, which is what was observed.

Raman testing is frequently done as a standard way to identify the composition of various gemstones, both natural and man-made, as it is relatively cheap to do, and is completely non-destructive. The Asha diamond simulant is the only diamond simulant in the world that employs a form of amorphous diamond pure enough to easily register under standard Raman microspectroscopy.

Test performed by: Intertek Northwest, NWTC Lab, England (July, 2004)

Equipment used: Confocal raman microscope with 785nm diode laser excitation

Contact Angle Goniometry
Purpose: To 'visually' show the amorphous diamond coating
Results: The Asha with coating showed roughly 300% difference in contact angle as compared to an uncoated Asha core. .

Below are photographs of the test performed on a CZ and on an ASHA diamond coated simulant. This test illustrates that the Asha has a lower coefficient of friction compared to an uncoated CZ. As you can see the contact angle of the drop on the uncoated CZ is 98.5 degrees (300% higher than the Asha). The drop clings to the surface of the CZ similar to the way a drop of water clings to glass. In contrast the contact angle of the ADT coated Asha is drastically lower at only 31.7 degrees.

The drop clings to the surface of the CZ similar to the way a drop of water clings to glass. In contrast the contact angle of the ADT coated Asha is drastically lower at only 31.7 degrees. Therefore dirt, grime, hand oils, lotion, etc will stick less to the Asha because of the diamond coating, and your stone will remain much cleaner than an ordinary CZ.

Test performed by:  Future Digital Scientific Laboratories (March, 2007)

Review by International School of Gemology
The International School of Gemology ( recently began investigating the claims made by the makers of the better known diamond simulants in order to start separating which simulant makers are telling the truth about their products and which are making fraudulent claims.

They did this by posing as a consumer and purchasing a loose simulant stone from the various diamond simulant websites. After receiving their order, they then subjected the received simulant to a series of test using standard gemological equipment to see what was reality and what was internet deception.

While the results are still pending on some of the other simulants, ISG has already published their findings on the Asha Diamond Simulant and with their permission, we are pleased to share their review in its entirety here on our site:

As previously stated, these tests were performed in the ISG gem lab using basic gemological tools available to the average retail jeweler on an everyday basis. Our purpose has been, and continues to be, to offer quality gemological expertise to the retail jeweler that can be used and duplicated for themselves using the knowledge and equipment that is within the reach of all local, hometown retail jewelers.
ASHA Diamond Simulant which claims to apply an Amorphous Diamond Treatment to the surface of a cubic zirconia.

What we ordered:
1.00 ct (diamond equivalent size) / 6.5 mm Round Brilliant ASHA Diamond Simulant

What we received:
1.84 ct / 6.5mm Round Brilliant ASHA Diamond Simulant

General Overview:
Gemstone arrived in excellent condition. No abraded facet junctions, no dings, no scratches. As promised, the gemstone is of the same size as a 1.00 ct diamond.

This is the best cut simulant I have seen to date. The closest thing to an IDEAL cut CZ that I have encountered.


Refractive Index:
Taken by the Jemeter Digital 90 the RI of the ASHA measures 2.183, which is in the upper range of the published refractive index for cubic zirconia.

The gemstone shows inert to Long Wave UV and Moderate Blue to Short Wave UV, again within the known range for cubic zirconia.

Hydrostatic Specific Gravity:
Based on the weight in air to water ratio, the Specific Gravity taken by hydrostatic method is found to be 5.22. This is significantly less than the published range of cubic zirconia.

By scratch test we found the stone was not scratched by another cubic zirconia. The stone was not scratched using a natural sapphire. However, when scratched by a diamond it did scratch as expected.

Conclusion #1:
Based on the above test results we concluded that the ASHA stone does, in fact, have a significant portion of the stone that is of a significantly lower specific gravity than cubic zirconia. This would result in the gemstone itself having a lower than expected specific gravity for cubic zirconia, which this stone does indeed exhibit.

Conclusion #2:
Based on the results of the hardness test, the ASHA exhibited a Mohs Hardness higher than a known control cubic zirconia and sapphire, and lower than a diamond.

We can only surmise that the ASHA is indeed fulfilling their claims to be adding a hybrid coating to the stone based on this stone showing both a lower density than cubic zirconia, and a greater surface hardness than cubic zirconia.

We do not have the necessary facilities to determine the exact nature of that coating, but given the above I personally feel confident that only a diamond-like substance could impart all of the anomalies to this gemstone that it presented in these tests.

Submitted for your consideration and review in hopes this will help provide clarification of some of the claims made by various sellers of diamond simulants.

Note: Copyrighted material - 2006, International School of Gemology

Credit to: International School of Gemology (
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