This subset of RAL Classic colours primarily contains shades of Blue colour. You will notice, that all colour codes in this range starts with RAL-5xxx, this is distinctive feature for this specific RAL color range. More purple or violet RAL colours are grouped under a different code range, you can browse those colours here.

Click any of these colours for extensive details and more similarly looking color swatches. If you're still not quite sure, using ral colour search might bring you the answers that you need.

Most people also find, that comparing RAL Colors side by side is also a very handy tool for colour selection.