We have recently imported this granite curbing that has integrated corners and accessory cone finials to enable the creation of formal garden beds, borders and planters. The cone finial sits nicely on each corner curb. These curbs can be dry set on a bed of crushed rock or a mortar bed for more permanence.
Granite curbing 5" x 5" x 18" curbs with split texture $25/pc
Granite curbing corners 6" x 6" x 6" w/split outside edges/thermal top $15/pc
Granite Cone finial 5" x 5" x 12" tall $125/pc