edging
There are several possibilities to make your pond clean. For the top edge you can choose different natural stone finishes, for a swimming pond you should finish with a rounded side.
Below are a few of the possible finishes.
Pond edges

1. Spotted Blue

2. Tibet Olivian Black

3. Mustang
Swimming pools

11. Spotted Blue

12. Tibet Dark Grey

13. Tibet Light Grey

14. Tibet New Black

15. Tibet Olivian Black

12. Tibet Dark Grey
Side wall finishing

21. Black Quartzite

22. Black Slate

23. Grey Quartzite

24. Rustic Sand

25. Rusty Silver

26. Rusty Quartzite

27. Rusty Slate

28. White Marble