May we suggest:
Aquamarine Bead Collar and Necklace - large and small
Here’s the pair together – the big beautiful Aquamarine Bead Collar and the longer, smaller, but still substantial Aquamarine Bead Necklace. The smaller bead necklace has a heavy chain that allows you to double it – as shown here. There’s another shot that shows what it looks like when full length.