Potters can do white or black foam to fit their boxes - you have to order it in addition to the cotton wadding, but the wadding is brill for keeping jewellery snug and safe in the post. They also do slim postal boxes and can print your logo on the box. Have never managed to find a "posh" box I actually like as much as the simple card ones
I use hinged leatherette boxes with my logo on.
I feel how I present my items is part of my identity and that fits with how I want to identify my brand and it doesn't add much to the finished price.
We use Westpack
http://www.westpack.com/
Ooh did someone say Opals
https://www.facebook.com/groups/500040476852371/
https://www.etsy.com/uk/shop/CabochonUK
www.glitterandgem.co.uk
When I was in France we had a big postal charge difference for anything under 3 cm so i used the slim postal boxes from karinakraft with my logo on , they are pretty good and a good price too
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