I like the big pearshaped aquamarine as a pendant on a simple chain like Maxima wore it during the silver jubilee dinner of then queen Beatrix.

Personally I don't like it as a pendant to the big(ger) bow brooches either. only attached to the small diamond bow brooch on a plain dress this pendant comes to it's justice IMO I think queen Maxima wore it like this in 2013/2014 in Spain.

But otherwise I agree with you that aquamarines would be a good option for Greece.