Professional Goldsmithing : A Contemporary Guide to Traditional Jewelry Techniques
by Alan Revere and George McLean (Illustrator)
This book isn't available in the UK, so I've listed a link to Amazon.com in the US. Full of tips which would take years to learn in the shop. Well written, good photos, lots of projects. A definite must for anyone working in gold or silver at any level.

The Art of Jewelry Making: Classic & Original Designs
by Alan Revere
All in color! Engraving, casting, fabricating, forging, soldering, and enameling. The techniques are varied and creative, just like the projects. Pins, earrings, rings, a necklace, a pendant, a bangle, and a cuff bracelet of extraordinary beauty and style make exceptional accessories. Compiled by an international award-winning jewelry maker, these outstanding examples will fill you with a passion for working with precious metals.

The Encyclopedia of Jewelry-Making Techniques:A Comprehensive Guide to Traditional and Contemporary Techniques
by Jinks McGrath
With easy understand and step-by-step instruction, this is a great book for a beginner in jewelry design. In this book, it shows most of useful tools and methods in jewelry making with clear images.

The Complete Book of Jewelry Making
by Carles Codina
After a brief discussion of basic metallurgy--alloying, smelting, annealing, and pickling--the book moves to essential jewelry-making techniques: cutting and piercing, soldering and other joinings, making closures and rings, and enhancing the surface: etching with acid, combining different metals, creating textures, and adding color.

Jewelry Design: The Artisan's Reference
by Elizabeth Olver
Excellent design source book .