ALGT Professional Laboratory for Diamond, Jewellery and Gemstone Reports

On the evening of April 28, 2026, during his visit to Shanghai, Belgian Deputy Prime Minister and Minister of Foreign Af...
20/05/2026

On the evening of April 28, 2026, during his visit to Shanghai, Belgian Deputy Prime Minister and Minister of Foreign Affairs Maxime Prévot warmly met with representatives of Belgian companies and the Belgian community in China at a welcome reception. ALGT Gem Laboratory was honored to be invited to this international China-Europe business exchange event.

As more and more Chinese jewelry companies expand into global markets, helping overseas buyers accurately understand product information has become an important part of the internationalization process. Without unified standards, differences in gemstone variety, treatment disclosure, quality characteristics, and nomenclature may easily lead to misunderstandings across different countries and markets.

In accordance with CIBJO international standards, ALGT provides professional testing reports for Chinese companies seeking to expand their overseas business. These reports help present product information in a format familiar to the international market. They not only enhance the credibility of the products, but also support Chinese companies in entering global markets more smoothly.

At the same time, ALGT also provides independent and professional testing support for overseas companies that source or process gemstones in China. By evaluating whether gemstones meet the relevant requirements under CIBJO standards, ALGT helps international clients reduce misunderstandings and risks caused by geographical distance, information asymmetry, or differences in standards between countries.

In global jewelry trade, a professional report is more than a test result; it is a foundation of trust between buyers and sellers. With its international professional standards, ALGT hopes to continue helping Chinese companies reach the world, while also supporting overseas companies in working with the Chinese market with greater confidence.

This Monday, ALGT’s General Manager and Chief Gemologist, Marc Segers, was invited by Sofie Vanheukelom, President of St...
20/05/2026

This Monday, ALGT’s General Manager and Chief Gemologist, Marc Segers, was invited by Sofie Vanheukelom, President of Studio Goudmijn, to give a lecture at Kasteel van Bokrijk in Belgium.

Studio Goudmijn is a professional community and educational institution for jewelry designers and goldsmiths in Belgium. Marc’s presentation offered Belgian goldsmiths and jewelry designers a clear insight into how a gemstone testing laboratory identifies gemstones and determines possible treatments.

During the lecture, Marc explained the role of different gemological instruments and how their results are interpreted by gemologists. He discussed how observations such as inclusions, chemical composition, spectral features, and other analytical data can support conclusions on gemstone treatment and, in certain cases, origin determination.

In the afternoon, INFINITY GEMS and Metro Stones, two gemstone companies, also shared their perspectives on the gemstone market from the dealer’s point of view. They additionally organized two hands-on gemstone workshops, focusing on sapphire and emerald, as well as garnet and spinel.

The event was a great success, bringing together education, market insight, and practical gemstone experience. We were delighted to see such strong engagement from the audience and to contribute to this inspiring professional exchange.

In today’s jewellery market, the naming of many stones as “Padparadscha” is problematic — or, to put it more mildly, doe...
18/05/2026

In today’s jewellery market, the naming of many stones as “Padparadscha” is problematic — or, to put it more mildly, does not comply with the internationally accepted grading standards for Padparadscha sapphires.

Mainstream international gemmological laboratories generally follow LMHC Information Sheet #4 when identifying and naming Padparadscha sapphire, in order to address the long-standing confusion surrounding this terminology in the global gemstone trade.

According to the LMHC definition:
“Padparadscha sapphire is a variety of corundum from any geographical origin whose overall colour appearance is a subtle mixture of pinkish orange to orangey pink with pastel tones and low to medium saturation when viewed in standard daylight — in the range between D50, 5000 K and D65, 6500 K — preferably with a Colour Rendering Index, or CRI, of 95 or higher.”

The LMHC also clearly specifies the circumstances under which a corundum should not be identified as Padparadscha.

1. if the stone has any colour modifier other than pink or orange, even when induced by scattering effects from tiny inclusions, or turbidity.
For example, in the report shown below, this pink-orange sapphire displays a distinct purplish tone. Therefore, it can only be identified as Purplish Pink Sapphire, rather than Padparadscha.

2. if the stone shows major uneven colour distribution when viewed with the unaided eye, table-up, within a range of plus or minus 30 degrees.
This means that when the stone is observed face-up with the naked eye, its colour appearance should be sufficiently even. If there is obvious uneven colour distribution, it should not be named Padparadscha.

3. if yellow or orange epigenetic material is present in fissures and affects the overall colour of the stone.
As shown in the image below, the right side of the gemstone represents its true body colour, while the orange colour on the left side is the result of interference from foreign material.
In other words, the orange component of a Padparadscha sapphire must come from the corundum itself, rather than from external orange or yellow substances present in fissures.

4. if the colour of the stone is not stable and shifts out of the Padparadscha colour range, for example shifting to pink, as determined by a colour stability test.
Colour stability is one of the mandatory requirements for identifying a sapphire as Padparadscha. If a stone’s colour changes significantly under testing and no longer remains within the Padparadscha colour range, it should not receive the Padparadscha designation.

5. if the stone has been treated by irradiation, lattice diffusion of foreign elements other than hydrogen, or if it contains glass-filled fissures and cavities, with or in combination with glass as a manufactured product.
Such treatments go beyond what is acceptable for a stone to be identified as Padparadscha under the LMHC guidelines.

6. if the stone has been dyed, coated, painted, varnished, or sputtered.

These forms of artificial surface or colour treatment also disqualify a stone from being named Padparadscha.
In other words, for a pink-orange sapphire to be identified as Padparadscha, it must meet all of the following criteria:

1. It must not show any colour modifier other than pink and orange. In an ALGT report, the colour description should only include Pink and Orange.
2. It must not contain orange or yellow inclusions that affect the overall colour. In an ALGT report, there should be no comment such as “Orange color is due to the orange inclusions.”
3. It must pass the colour stability test and show no visible fading. In an ALGT report, this may be stated as: “The ALGT fade test was performed and showed no visible fading.”
4. It must not have undergone treatments such as lattice diffusion, filling, irradiation, coating, dyeing, or any other treatment beyond accepted pre-treatment conditions.

😃We are excited to announce that the new ALGT website : https://algtlabs.com is finally online!👏👏👏With its new structure...
06/05/2026

😃We are excited to announce that the new ALGT website : https://algtlabs.com is finally online!👏👏👏

With its new structure, the website is designed to help you find the information you need more easily and efficiently.

🚩On the top-right corner of the homepage, you will find the Report Check function. Next to it, you can also select your preferred language. The website is now available in English, French, Chinese, and Dutch.

🚩We have also added a new section explaining how to submit a gemstone or jewellery item to our laboratory. You can either visit the lab directly or send your item by shipment.

🚩Our services and equipment are now clearly presented online, helping you choose the most suitable service or report for your gemstone or jewellery. You can also learn more about the instruments we use for gemmological examination, including treatment detection and origin determination.

🚩You are also welcome to take a virtual tour of our laboratory through the link provided on the homepage.

🤩Visit our new website and discover ALGT online!

As gemologists, it is essential for us to stay up to date with the latest developments in the world of gemmology. That i...
23/04/2026

As gemologists, it is essential for us to stay up to date with the latest developments in the world of gemmology. That is why our General Manager, Marc Segers, together with CEO Mingyue Yang, travelled to Idar-Oberstein last weekend, on April 18 and 19, to attend the Pearl Conference.

During the conference, specialists from DGemG, SSEF, Jagiellonian University in Krakow, LFG, and DSEF German Gem Lab delivered presentations covering various aspects of pearls, as well as the technologies and methods used to determine whether a pearl is natural or cultured. Topics also included identifying the type of mollusk from which a pearl originated, estimating its period through C14 dating and DNA analysis, and exploring the role of pearls in history and jewelry during the Renaissance period.

The new session of our gemstone workshop will begin in two weeks.Starting from Monday, 4 May, each gemstone module will ...
22/04/2026

The new session of our gemstone workshop will begin in two weeks.

Starting from Monday, 4 May, each gemstone module will run for three days. We will begin with Sapphire. Classes will take place daily from 9:00 am to 5:00 pm, including two coffee breaks and a one-hour lunch break. The morning sessions will focus on theory, while the afternoon sessions will be dedicated to practical training.

Course Structure
Each gemstone module lasts for three intensive days, providing comprehensive coverage of the essential topics:
• Sapphire: 3 days (4th-6th of May)
• Ruby: 3 days (11th-13th of May)
• Emerald: 3 days (19th-21st May)
• Total duration: 9 days

Flexible Enrollment & Pricing
Participants may register for one, two, or all three modules. There is no obligation to complete the full course.
• €500 per gemstone module (3 days)
• €1,400 for the full 9-day program
• Prices are excluding VAT

What You Will Learn
• Gemstone fundamentals: identification of natural and synthetic stones, origin determination, and quality grading
• Treatment detection: understanding and identifying modern enhancement techniques
• Advanced technology: hands-on training with cutting-edge instruments used in professional gem laboratories

From now on, you are welcome to visit ALGT to register.

A Rare 4 ct Cat’s-Eye Emerald Examined by ALGTALGT recently examined a remarkable 4-carat emerald displaying a distinct ...
02/04/2026

A Rare 4 ct Cat’s-Eye Emerald Examined by ALGT

ALGT recently examined a remarkable 4-carat emerald displaying a distinct and well-defined cat’s eye effect.

Using Raman spectroscopy, we first confirmed that the gemstone is indeed a natural emerald. The stone shows a vibrant green color, good transparency, and is polished as a cabochon, a cut style that beautifully highlights its optical phenomenon. Under a single direct light source, the emerald reveals a sharp and mobile chatoyant band centered across the surface, a striking cat’s-eye effect rarely seen in emeralds.

Under magnification, we observed numerous parallel elongated tube like inclusions. These well oriented inclusions are responsible for the gemstone’s exceptional chatoyancy.

To investigate possible clarity enhancement, the emerald was examined under long-wave UV light (365 nm). No anomalous fluorescence zones were observed, indicating the absence of residual oil or resin. In emeralds which have undergone the clarity enhancement, such fillers often produce noticeable yellowish-green or bluish-white fluorescence.

For further confirmation, FTIR analysis was carried out. In the 2800–3100 cm⁻¹ region, no absorption peaks related to oils or resins were detected. The absence of clarity-enhancing substances in a cabochon-cut emerald is particularly unusual and noteworthy.

The UV-Vis spectrum revealed characteristic Cr³⁺ absorption features, including a strong band near 430 nm and a broad band near 600 nm, confirming the emerald’s color origin. In addition, a distinct Fe²⁺ absorption band near 850 nm indicates a relatively high iron content.

Finally, EDXRF analysis, together with the spectroscopic and microscopic results, supported the conclusion that this emerald is of Brazilian origin.

A fascinating example of how advanced gemological testing can reveal both the beauty and the story behind an extraordinary gemstone.

02/04/2026

This image shows a negative crystal with a carbon dioxide bubble inside an unheated Sri Lankan sapphire. Because inclusions like these cannot survive heat treatment, they are considered strong evidence that the sapphire is natural and unheated. 💎

23/03/2026

ALGT IS NOT ONLY A COLOURED STONE LAB, WE ARE ALSO DIAMOND EXPERTS.

Many people think ALGT is only specialized in coloured stones, but that is not the full story.

ALGT is also fully qualified in DIAMOND TESTING AND GRADING!

Our diamond experts bring years of experience from renowned institutions such as De Beers, IGI, and HRD. In addition, our director Marc Segers received the Gold Medal for Expert in Diamond from the Koninklijk Instituut der Eliten van den Arbeid (KIEA), the highest professional distinctions in Belgium.

At ALGT, we offer:
Natural Polished diamond grading
Synthetic diamond grading
Treatment detection
Rough diamond grading
Diamond jewellery grading

And one more piece of good news:
Synthetic diamond grading is only €25 per stone, regardless of carat weight.

Because at ALGT, diamond expertise is just as much a part of who we are.

AT ALGT, EVERY SINGLE STONE MATTERS!☝️A truly breathtaking Sri Lankan sapphire jewellery set has just arrived at ALGT.😍F...
23/03/2026

AT ALGT, EVERY SINGLE STONE MATTERS!☝️

A truly breathtaking Sri Lankan sapphire jewellery set has just arrived at ALGT.😍

Featuring a necklace, a pair of earrings, and a bracelet, this set is beautifully designed, elegant, and full of charm. The rich blue sapphires and exquisite craftsmanship make every piece shine with timeless beauty and sophistication.🤩

At ALGT, our work goes far beyond checking only a few randomly selected stones. We examine every single sapphire in the set, one by one, carefully assessing its measurements, colour, clarity, treatment, origin, and other key characteristics. Because when it comes to exceptional jewellery, every stone matters!😁

Adres

Diamond Plaza Hoveniersstraat 55 Bus 88
Antwerp
2018

Openingstijden

Maandag 09:00 - 17:00
Dinsdag 09:00 - 17:00
Woensdag 09:00 - 17:00
Donderdag 09:00 - 17:00
Vrijdag 09:00 - 17:00

Telefoon

+3235350888

Meldingen

Wees de eerste die het weet en laat ons u een e-mail sturen wanneer ALGT nieuws en promoties plaatst. Uw e-mailadres wordt niet voor andere doeleinden gebruikt en u kunt zich op elk gewenst moment afmelden.

Contact

Stuur een bericht naar ALGT:

Delen