by John Niggl
Last week we covered inspection methods and assessing quality of casting, soldering and glue assembly. Jewelry items need not only be highly presentable and appealing, but they also need to stand the test of time. There are few other products for which expectations of durability and craftsmanship are higher. That’s why our focus this week is on stone placement and setting. A ring with the best casting work and the most highly-prized gemstones can really take a tumble in terms of quality if those gemstones are not properly set. Let’s jump right back into Jewelry QC by picking up where we left off. Take a look at how Jewelry QC experts verify which items make the cut and which need reworking.
When assessing stone placement, make sure that the table and girdle of the stone are even and without any noticeable slanting. The stone should sit firmly and securely regardless of setting style. This means making sure there are no gaps in the setting and the stone doesn’t fall out when jostled. For rings, the lower tip of the stone should not extend through the finger rest or touch the skin when worn. For pendants, the stone should not extend beyond the base of the setting. Whenever there are several adjacent stones, generally, the stones should be as close together as possible.
Consistency and firmness to the stone are the most important qualities to look for in prong settings. The tip of each prong should be firmly pressed to the stone without any space in-between. Prongs should not be bent, but instead, they should be positioned symmetrically and have the same length and form. The same is true for jewelry with “V-shaped” setting edges. The two arms of the “V” have equal angles within the piece and should not press against each other too closely. Lastly, the prongs should be correctly polished and finished. Any over polishing can make the prongs to thin. Keep your eyes out for the following defects related to polishing the prongs:
- Tool marks or scratches
- Excess metal
- Rough edges
- Fire scale
- Visibly porous areas or holes
- Casting residue
- Polishing residue
As with prong settings, symmetry and stone security are important. However, whereas prongs simply need to hold the stone securely, a bezel must fit the stone like a glove all the way around. There should be no gaps, metal or metallic residue between the inner edge of the setting and the stone. A quality piece should not have any jagged or uneven rims on the bezel. For backset bezel settings, the table of the stone should be positioned as high as possible above the inner bezel edge.
A jewelry piece that contains several gemstones often has them set in a channel. On such pieces, all stones in the channel should be set in the same plane. This means no stone should be crooked or set at a different height than neighboring stones. While a minute gap is often permissible for round stones set side-by-side, such a gap typically needs to be homogenous throughout the entire channel. Stones of other shapes are generally set girdle-to-girdle without any gaps in-between. Finally, the edges of the channel should be straight and without deviations.