Gemological diamond appraisal for jewelry and diamonds
Would you like to know what your diamond or diamond jewelry is worth?
The unique sparkle of a diamond is determined by its brilliance, play of color, clarity and cut. The colors of a diamond can be as dazzling as the gemstone itself: from colorless stones to pink, green, blue and black.
Diamonds can be found in all the different shades of the color spectrum. The color scale for colorless diamonds starts at D (very fine) and extends to Z (strongly tinted). After Z come the fancy-colored diamonds – so-called “fancy-colored diamonds”, usually referred to as “fancy diamonds” for short. Natural diamonds in pink, green and blue are rarely as intensely colored as the colored gemstones ruby, sapphire or emerald.
Which diamonds does the GLA value?
We exclusively evaluate diamonds in cut form. Please note that, unlike other gemstones, the origin of a cut diamond cannot be determined. At the GLA, colorless and fancy diamonds are graded and assessed.
How is the value of a diamond determined?
The quality of a diamond is determined according to international guidelines. The 4 Cs are determined in diamond grading:
- Carat (weight)
- Color (Color)
- Clarity (purity)
- Cut
Most diamonds are colorless to slightly tinted. In this color range, diamonds without any external tinting are traded at the highest prices. With fancy color diamonds, the color determines the value. This is defined by the base color, any second or third colors, color intensity and saturation.
A key indicator of the high quality of a diamond is whether it has any inclusions. If no inclusions are visible under a magnifying glass when analyzed by a trained expert at ten times magnification, the stone is described as flawless. Essential for the brilliance (the “fire”) of a diamond is a flawless cut, which unfolds its optical effect.
What influences the value of diamonds?
Natural, untreated and flawless diamonds are extremely rare. Nowadays, there are various treatment methods to artificially improve the color and purity of diamonds. Furthermore, diamond syntheses, i.e. artificially created diamonds, are also increasingly available on the market.
The following factors reduce the value of a diamond or your diamond jewelry:
- Color treatments for colorless and colored diamonds (fancy color)
- Inclusions visible to the naked eye
- Damage and signs of wear
- Cleanliness treatments such as crack filling or laser drilling to make inclusions less visible
GLA – Your partner for diamond appraisals
Founded in 1979, Gemmologisches Labor Austria (GLA) has enjoyed an excellent reputation throughout Europe for over 40 years for its objective and independent appraisals of diamonds, colored gemstones and jewelry. The sworn and court-certified expert MSt.in Adeline Lageder, who has headed the laboratory since 2006, has many years of experience in the grading of diamonds. Determining the type of diamond is essential for the analysis and is carried out using scientific tests (FT-IR spectrometer).
This is how your diamond appraisal is carried out:
In addition to weight, color, clarity and luminescence, the diamond certificate describes the quality of the cut (cut type and shape, proportions, symmetry and polish, as well as the condition of the rondiste and calette). Luminescence is the luminous appearance of a diamond or gemstone when it is exposed to ultraviolet light (366 nanometers).
Diamonds can have a laser engraving on the rondiste – the widest part of the stone. However, this can be polished out or falsified. For this reason, the conformity of a diamond or gemstone with a report from another laboratory must be checked using other parameters.
The valuation of diamonds is based on the quality criteria of the grading system in accordance with international guidelines. International price lists and/or price comparisons are used to determine the value at the desired trade level. Our laboratory is equipped with state-of-the-art instruments to provide diagnostic and/or appraisal reports that are recognized by courts, banks and insurance companies as well as renowned auction houses and gemstone dealers.
We will be happy to provide you with a free initial consultation.
Make an appointment for your diamond appraisal now!