18K golds største fordel er dens renhed. Som den reneste form for guld, der er praktisk at bruge i en forlovelsesring, en 18K guldring giver det smukke udseende af næsten rent guld med de fleste af de praktiske fordele ved en legering.
Denne ekstra renhed kan især være tydelig med 18K gul eller rosa guld, which tends to show a warmer, more vibrant tone in 18K than in 14K gold.
The higher purity level of 18K gold also makes it less likely to trigger skin allergies than 14K or 10K gold. Although 18K gold still contains nickel and other alloy metals, they’re only present in small quantities, making the risk of contact dermatitis or other allergic reactions very small.