Jacob Hull was working in Denmark - mainly in the 1970's - producing silver and silver plated jewellery.  It is very distinctive in style - large pieces sometimes with a lump of amethyst or similar, sometimes in a sunburst pattern etc.  He made some pieces in silver - these would have been more expensive and I have never had one.  Mostly it was in silver plate.  His work was marked J. Hull and Denmark.  If it was silver it was marked as such.  I often see pieces that are silver plate being sold as silver - because they are marked and look good - so do check.  Also some of his pieces are marked B & D.  These pieces would have been commissioned by Buch & Deichmann.  A good site to look at for his work - and other silversmiths - is scandinaviansilver.co.uk - the pieces have risen in price recently.