Hlo buddy, there is no specific dress code provided by CBSE. But you should not take these things during exam :-

1. No Belt , So wear tight pent

2. No stationary (no pens, no pencil,  no blank page )

3. Not any electronic item ( wrist watch is included) 

4.No purse

5.Big Shoes

6. No bracelet 

So I suggest you to not take a finger rings. It's just one day exam. 

All the best buddy. 

here is no specific dress code this year in JEE MAIN. But i suggest you to donttake these things along with you in exam :—

1. First of all, all types of electronic item (wrist watch included).
2. No stationary(no pens, no pencil).
3. No belt, so wear tight pant.
4. Tshirt with some Design on front and back.
5. Any type of bracelet.
6. Biggy shoes..
7. Any water bottle.. (but i take a cold drink bottle along with me)
8. Purse……

So i suggest you to not take a finger ring.

CBSE has not specified any dress code for JEE Main 2018. However, some pointers are wise to keep in mind regarding what to wear and what not to wear to the exam hall.

Do not wear anything with too many pockets.

Do not wear jewellery.

Wear simple, clothes without accessories.

Preferably wear t-shirt and jeans, or top/kurti with leggings.

For JEE Advanced 2016, a dress code was introduced for the examinees. However, for JEE Main there was no such implication. Same happened in 2017, there was no such restriction for JEE Main 2017. So, those appearing for JEE Main 2018 can wear whatever they wish but it should be comfortable. To be precise, there is no dress code for JEE Main 2018.