Mastering the method of manufacture

Hand construction—a very broad subject

Methods of hand construction include any of the previously discussed, but generally speaking, the term ‘hand-fabricated’ means the piece was made completely by hand. Take, for instance, a novelty brooch—the figural portion is cast, the original mould is hand-carved, and the pin stem is made of hand-drawn wire, hardened so as not to bend. And finally, the rotating safety clip is also handmade and assembled. Processes used include: drawing wire, sawing, piercing, soldering, filing, forging, drilling, etc. Tool marks are our salvation. And remember, just because a piece was handmade doesn’t mean it was well done.

What to look for in a hand-fabricated piece:

• Tool marks made by a saw, file, and/or hammer. The best way to recognize these marks is to examine pieces you know have been hand-fabricated. A good example is repoussé, which is a decorative technique whereby 3-D designs in high or low relief are formed from the backside with specialized tools. It doesn’t hurt to take a goldsmithing class or two to become familiar with the principles of construction. There are also resources online that explain in detail the processes and are well worth a look.
• Flashing in the drill holes might be seen in less expensive or sloppily made jewellery.
• Finishes—examples include Florentine, planished, textured, and bloomed.² Look closely at the detail; is it so uniform as to be done by a machine? Or is there some variance in the texture? Was the piece polished so heavily it might have had another finish when it was first made? Is it an antique ‘bloomed’ finish or just a more modern sand-blast? Florentine finishes can help date your piece, while more abstract textured finishes might point to a certain designer.

Whether the appraiser uses a narrative to describe the item or a list model, the method of manufacture can be referenced any number of ways. Here are a few examples:

• Composed of cast and pre-fabricated components;
• Assembled from hand-fabricated components;
• Die-struck and assembled;
• Custom CAD/CAM and cast;
• Custom wax-carved and cast;
• Assembled from custom-cast and pre-fabricated components;
• Machined and assembled; or
• Mass-produced and assembled.

Practice and experience are required to recognize these various manufacturing methods. When starting out, take the time to examine known pieces; if you work in a jewellery store, examine the inventory. Become familiar with various companies’ methods of manufacture and memorize the way these pieces look. Working an auction preview is one of the best ways to examine antique and period pieces; see if there is an auction gallery in your area.

Detail is critical to compose a well-written appraisal. Not only can it elevate your appraisal documents above the competition, it greatly assists your client when they experience a loss.

Notes

¹ The finish of a fine cast piece would have been given much more attention. Holes would have been thrummed (i.e. polished with a string), removing telltale signs
of that cast ‘skin,’ making this method more difficult
to detect.

² Bloomed gold is the process of immersing the finished piece in a hot bath of hydrochloric acid, saltpeter, and salt and water to dissolve the alloys to bring the fine gold to the surface. This was extensively done up to the Victorian era, and is most prevalent in the art nouveau period. At that time, gold was alloyed with copper, and this process removed the pinkish colour of the piece. Another way to achieve this high-karat look is fire gilding; an amalgam of mercury and gold is applied as a paste to an object and then exposed to heat to vaporize the mercury. Both methods will only be seen on antique pieces.

Carole C. Richbourg is an independent gemmologist/appraiser in Northern California and has been appraising full time since 1999. She is an accredited senior appraiser, master gemmologist, and a fellow of the Gemmological Association of Great Britain. Richbourg is co-instructor for the American Society of Appraiser’s (ASA’s) GJ-202 appraisal report writing for insurance coverage class. She may be contacted via e-mail at carole.richbourg@finejewelryappraiser.com.