Shatter polish was a popular trend in nail polish around 2013-2014 I think, before nail art took over. I thought it looked cool, so towards the end of the trend I bought 2 shatter polishes on sale: Black and Silver.
I still wear them. The way I like to use them is to apply them to my regular polish once it starts to wear off, thereby extending the life of my nail polish. This way I can wear ordinary polish for about a week, and then get a couple of days extra wear by applying the shatter polish (silver or black depending on whether I am wearing light or dark polish) which handily covers up any chipping around the edges of the nails. I know the trend is over, but I still think it looks cool.
I purchased the black shatter nail polish when it first came out and I really liked it, i tried it over a lot of colours from OPI. It was really fun to watch it form the shatter effect. When applying onto my nails I had to make sure I had a good amount on the brush and only do one coat because it doesn't work very well if you apply more coats, it goes streaky and doesn't shatter properly. I also noticed it started going really thick in the bottle and was hard to apply so had to throw it out after awhile. Probably won't buy it again I prefer my nails just one colour but maybe one day if they still have it I would purchase it for my daughter to try.