What surrounds the gravel circle? Lawn, soil or paving?

surrounded by soil,

Depending on how large the circle is, small stone setts might work - otherwise you're stuck with the deeply unattractive log roll or that nasty plastic green edging strip meant for lawn edges. Alternatively, dig out a small trough about 8 inches deep, fill it with a concrete mix and insert pebbles into the top and let it set, then place the gravel in the middle.

thanks

Another alternative is brick pavers (the sort people use for block paving in front gardens for parking the car on). This is what I have used to edge a gravel path on my front garden. You should be able to buy them at a builder's merchants and decent firms will just sell you as many as you need

The small setts are easier to fit around a circle,and finish it off nicely..the brick pavers look better on straight edges,I think.We did our circle of gravel a few years ago,and it works well...plants in the borders will help to soften the edges..or some alpines or grasses in the gravel,also look good...great for standing pots on too..good drainage,and helps to keep snails and slugs off !