All three start from the same pure gold, then take their colour from the alloy mix. Yellow gold uses silver and copper in roughly equal parts, giving the warm tone people associate with traditional gold jewellery.
White gold uses silver, palladium or nickel to pull the colour toward silvery white, then most pieces are plated with rhodium to give a brighter, whiter finish that may need re plating every few years. Rose gold uses more copper, which gives it the pink to red tone that has been popular for the last decade, and the higher copper content also makes it slightly harder than yellow or white gold.
The karat (9ct, 14k, 18k) refers to the gold purity and is separate from the colour. You can have 18k yellow, 18k white and 18k rose gold, all with the same gold content but a different alloy recipe.
Read more: everyday rings collection.