You can purchase a unit such as this, http://www.suttontools.co.uk/microplate-unit.html, but there are coshh considerations and I would think that it could be quite time consuming. On the other hand, there are platers out there...I haven't used these, so I can't make a personalrecommendation, but here are some Birmingham Jewellery Quarter one's turned up by google....http://www.dmjewellery.co.uk
http://www.bellejewelleryltd.com
http://birmingham.cylex-uk.co.uk/plating.html

Perhaps if you go down this route you'd be kind enough to let everyone know how you got on.
Best of luck,
Tabby x