Here is a guide for 11 miscellaneous achievements around Paradise Killer, with this one being the fifth one.
1. If you go to the yacht in the north-west end, and take the elevator up, there will be a pyramid in front of a plaque to the left of the elevator here at the top.
2. You need to collect like 11 red gems, one being right there by the plaque.
3. hard to describe, but half are around there on the ground. 4 are up the tower, all requiring parkour, and half require jumping onto different levels half way up the tower.
4. Two are on two roofs next to you, where the footbath is.
5. Put them all on the plaque for the achievement. Hope this helps, guide makes more sense!