Yes, the regulations on what can and cannot be worn are rather complicated. Here is a typical inquiry:
I have seen pictures of women wearing belts, long necklaces and strings of beads on their torsos. I thought that was illegal. Also, I have waist-long hair. What are the exact regulations?
Anything that doesn’t extend below the neckline - necklace, hair, etc. - is legal. It is also acceptable if your hair falls down over your shoulders. It should not extend lower than the small of your back and should never cover any part of your bottom.
Your hair and necklace should be kept away from your breasts, and in particular your nipples must be clearly visible. It’s best if your hair is tied back, and if you have a long necklace, it should rest in your cleavage.