10 Kt Gold Pin's Hallmark Trefle Diamond Nielsen Unisex. AC Nielsen pin in 10 carat gold, hallmarked with clover. A small diamond of approximately 0.05 carats. The clip is gold plated alone, the Nielsen pattern is gold. Approximately 2.2 cm by 0.8 cm. Its weight, without the clip approximately 2.5 g with the closure system approximately 4 g.