Unfortunately, 18K gold’s biggest advantage — its purity — is also its biggest disadvantage. Due to its higher percentage of pure gold, 18K gold is quite noticeably softer and easier to scratch or dent than 14K gold.
This means that if your fiancé-to-be works with her hands or has an active lifestyle, an 18K gold ring might not be the best choice.
Another disadvantage of 18K gold is its price. As we briefly mentioned above, 18K gold costs a fair amount more than 14K gold, with most 18K gold engagement rings priced at 150% a 200% as much as their 14K counterparts.