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What is Top Wesselton?
Traditional European Colour Grading System
Historical context
Before the GIA (Gemological Institute of America) color grading system became the international standard, European diamond traders and jewelers used their own terms to describe color. “Top Wesselton” was one of those – derived from a diamond mine called Wesselton in South Africa, which was known for producing high-quality stones.
Regional tradition & consumer familiarity
In countries like Germany, Austria, Switzerland, Sweden, Norway and Denmark, many jewelers still use terms like River, Top Wesselton (TW), and Wesselton (W) because: Consumers are familiar with them, Jewelers have used them for decades and it adds a sense of tradition and regional trust
Old European Term – GIA Equivalent
River – D-E
Top Wesselton – F-G
Wesselton – H
Top Crystal – I-J
Crystal – K
So, a Top Wesselton diamond is essentially a high-quality near-colorless stone (F–G on the GIA scale).
The origin: Wesselton and the mines of South Africa
In the late 19th and early 20th centuries, when diamonds began to be mined on a larger scale in South Africa, several major mines emerged, including the Wesselton Mine in the Kimberley region.
Diamonds from the Wesselton mine were especially prized for their brightness and whiteness.
As diamond trading developed in Europe, traders began to associate color quality with the names of mines.
Terms like “River”, “Wesselton”, and “Cape” were born, named after rivers and mines that produced diamonds of certain color qualities.
How the old scale worked
Unlike the standardized GIA D–Z scale (created in the 1950s), the European system was more descriptive and experience-based. Here’s how they used it:
River: the whitest diamonds, as “pure as mountain river water”
Top Wesselton: slightly less white but still excellent
Wesselton, Top Crystal, Crystal: increasingly more yellow tones
Cape: distinctly yellowish stones, often from the Cape Province of South Africa
These names became part of the diamond trade vocabulary in Europe, particularly in Germany, Switzerland, Austria, and Scandinavia.
Why it survived (even after GIA came along)
When the GIA introduced its D–Z scale in the 1950s, it quickly became the global standard – especially in the US and international trade. But in Europe, the older system persisted for several reasons:
Tradition: jewelers and customers were already used to it.
Trust: terms like Top Wesselton became a shorthand for quality – consumers associated them with prestige.
Marketing appeal: some felt that words like River or Top Wesselton sounded more luxurious than just a letter.
Certifications: European gemological institutes (like HRD or IGI) often used both systems in parallel for clarity.
Today: A dual system
Today, both systems are often used side by side on diamond certificates in Europe. For example:
Color: Top Wesselton (F–G)
This helps bridge tradition and standardization, allowing European jewelers to maintain their heritage while aligning with international trade standards.