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3 results for “9 carat vs 18 carat” in Science
Science · 9 August 2026
The Metallurgy of Karat
…e the engineering lives. · Karat is a fraction, not a quality grade: 24 parts by mass, so 18k is 75.0% gold and 9k is 37.5%. · Pure gold measures roughly 25 HV on the Vickers scale — softer than a fingernail can dent — which is why it is alloyed before it is worked. · Colour is s…
Tomas Herrera · 16 min read
Science · 8 August 2026
The Metal That Went Medical
…o discovered colloidal gold? Michael Faraday prepared and studied stable gold colloids in 1857, correctly concluding that the ruby colour arose from finely divided metal rather than a dissolved compound. Some of his original preparations are still in the Royal Institution's colle…
Amara Okonjo · 15 min read
Science · 10 August 2026
Where Gold Actually Comes From
Every gram of gold on Earth was manufactured in an astrophysical catastrophe, arrived here after the planet had already formed, and was then concentrated by hot water. Three separate accidents, none o…
Tomas Herrera · 18 min read
