I did this quickly so I don't have any step by step pictures, sorry!
First I started with my base coat and then China Glaze Rich & Famous.
Next I created a triangular shape at the base of my nails using Illamasqua Baptiste. I used a nail art brush but if you don't want to do it freehand just place some tape on your nails leaving the shape at the base of your nails and paint over it. Make sure the tape is stuck to your nails really well because you don't want excess polish running under the tape and ruining the shape. Try to wait until the polish is dry before peeling the tape off.
Then I went over my entire nail with a coat of OPI Wing It! and added a clear rhinestone in the centre of the triangle.