Latest GRS News


Video: Mozambique Ruby Collection – A Lifetime Experience

Follow Dr. Peretti around the world to discover the magic of Mozambican rubies. From rough to polished. The journey commences at the Gemfields ruby auction in Singapore, moving on to Sri Lanka and Thailand for cutting and polishing until the finished gem can be unveiled.


Color stability test: Overview of “type” classifications

GRS Laboratories now offers color stability testing services at all laboratory locations Color fading is a natural phenomenon observed in certain gemstones, particularly with orange to yellow sapphires. In most cases this phenomena is reversible and occurs when the sapphire is exposed to a certain type of light. The light sources emission energy will eventually […]


Introducing GRS brilliancy-type “vibrant”

A new quality concept introduced to GRS gemstone reports – GRS brilliancy-type “vibrant” GRS introduces a new quality concept in the form of brilliancy awards for stones perfectly cut and with excellent clarity, very low degree of extinction and even color distribution. The best spinels from Mansin and Namya (Burma) or Paraiba-type tourmalines from Brazil […]


Reply to CIBJO Gemmological Commissions’ special report on sapphires heat treated under pressure

On 23 October 2019, the CIBJO Gemmological Commission released a special report an a variety of topics that will be discussed during the upcoming CIBJO congress in Bahrain. One of the topics to be addressed is the separation of sapphires that have been heated under elevated pressure. In this particular report GRS was cited as […]


Retake of GRS presentation on HPHT-treated sapphires from 2019 GILC meeting in Tucson, AZ

One of the topics discussed at this year’s GILC meeting in Tucson, AZ (held on 4th February 2019) was “Pressure /Temperature Corundum Treatment”. GRS had been invited in order to present our findings on the topic. Mr. Edward Cleveland, research staff at GRS in Bangkok, represented GRS at the event and gave a presentation called “HPHT (PHT) […]


Q&A on PHT-treated sapphires published in Southern Jewelry News

Sapphire, as well as most colored gemstones today are routinely treated to improve their appearance and increase their salability. Simple heat application, often called ‘cooking’ is an ancient method of enhancing colored stones. Depending on the stone itself, other forms of enhancement may be applied. Diffusion heats sapphires at a high temperature and adds certain […]


New types of synthetic periclase identified by C2S inclusions – dicalcium silicate cement hardener

Naturally occurring periclase is a relatively common mineral phase. Due to its small crystal sizes, it never gained recognition in the gem-industry in terms of commercial importance. Synthetic periclase is commonly used for technological applications and is available in large quantities and sizes (Joachin et al., 2012). In the past, synthetic periclase was marketed in […]

Alerts, News

AGTA announces guideline of full disclosure for pressure and heat-treated sapphires

AGTA announces guideline of full disclosure for pressure and heat-treated sapphires (GRS type “PHT” or HPHT). GRS welcomes this decision. AGL and then AGTA have also adapted GRS’ position of full transparency which stands in sharp contrast to the recent decision made by LMHC (Laboratory Manual Harmonization Committee). LMHC has decided not to distinguish or […]


Identification and characteristics of PHT (‘HPHT’) – treated sapphires – An update of the GRS research progress (update 12 November 2018)

A series of peculiar events that commenced in 2015 brought a degree of uncertainty to the Sri Lankan gemstone industry. Sri Lanka is known as the world’s foremost producer of ‘heated’ corundum. So far only corundum of higher clarity has been used to produce clean sapphires. It was noticed that a few buyers began purchasing […]


Spinel formation by sulphur-rich saline brines from Mansin (Mogok area, Myanmar)

During the last 2 decades, one of the authors has mapped the mineral occurrences in the Mogok valley and registered the mineral assemblages of approximately 100 spinel mines in a profile of 30 km length (first part published in Peretti et al., 2007 and Peretti & Tun 2016). Abstract from 15th Swiss Geoscience Meeting, Davos […]