There are many similes in this chapter. Their purpose is to describe the beauty of the woman. The woman is described as the epitome of beauty in ancient Israel. Not all cultures share the same the same standards of beauty. In 7:1-9 the man speaks to the woman. In some versions this is 7:2, the second verse of chapter seven.
"The curves of your thighs are beautiful like the beautiful curves of jewel that a skilled craftsman has made". The word "thighs" refers to the hips of a woman and the part of her legs that is above her knee.