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Enlarging Wedding Rings
When a plain band needs to be enlarged slightly it is often possible to achieve this through mechanical stretching. The number and variety of tools made to achieve this give some indication of how common a repair this is! Stretching is faster and less aggressive than the alternative of inserting an extra piece of metal and should always be considered.One device uses an attachment for a rolling mill to redistribute the metal in such a way that the ring is made larger. If the shank is made thinner, the metal that use to be seen as "thickness" has gone somewhere. Where? It has been pushed outwards, or converted to length, making the ring slightly larger.
Another alternate is to anneal the ring, then slide it onto a lightly oiled steel ring mandrel. Tap the ring gently with a wooden, leather or plastic mallet as shown in figure 13.7a to stretch it. Because of the tapered nature of the mandrel it is important to take the ring off periodically, invert it, and repeat the process.
A variation on this that avoids the possibility of marring a ring with mallet blows is the use of a tool called the Schwaan Ring Stretcher. The tool consists of a tapered mandrel with a hollow core that has been split into four vertical segments (figure 13.7b). The ring is put onto this rod and a smaller solid steel taper is driven into the first unit with a mallet. This has the effect of stretching the petals (and therefore the ring), though there is no direct contact with the ring itself. This has to be done slowly with great care so that the ring doesn't break.
Figure 2 shows a stretching machine developed by the Fisher Company in Pforzheim. The machine uses a internal bushing of the intended size to prevent the stretching process from going too far, and includes a copper ring that protects the jewelry piece from being damaged.
No matter how sophisticated the tool, any stretching will stress the metal and there is always a risk of the ring snapping. More than that, there is a limit to how far a ring can be stretched. As mentioned, it's always worth considering but there are many cases where a more radical technique will be needed.
Figure 2
Enlargement of Gem Rings
Rings with stones cannot be stretched on a mandrel because of the stress this puts on the stone. There is a danger of breaking the gem, or at least popping it out of its setting. When stones are involved, and if the enlargement is slight, a tool like the one shown at figure 13.8 is recommended.The device has a number of dies of different shaped grooves that mimic the cross section of the ring shank. Select the one that corresponds to the ring being stretched and attach it to the vertical post of the machine. The ring is then forced against this to locally "forge" the shank. As mentioned above, the action exchanges thickness for length, pressing the ring in such a controlled way that the change is unnoticeable. Of course there is a limit to the stretching that can be done this way, not only because the metal hardens at it is stretched, but the shank could eventually be made too thin.
If the ring contains heat sensitive stones then this complicates soldering. Amber, coral and pearls are so sensitive that such stones need to be removed if a normal soldering flame is used. Other sensitive stones should be taken out if possible. If this is not possible, then they need to be protected against heat. Numerous possibilities have been recommended, all of which are based on the concept that the stone is packed in moist material so that the heat of soldering boils the water instead of being transmitted to the stone.
Sizing Down Plain Bands
When a basic wedding band or similar ring needs to be made a little smaller, the first method of choice is to compress it. Like its corresponding partner, stretching, this is fast, efficient and the least intrusive process. And like stretching, it can only be used when the change in size is small.If the ring is made of several metals, for instance of white gold and yellow gold, this method is limited and might even result in breaking the two metals apart because they have different rates of compression. If the outer surface of the ring is faceted, chased or engraved, protect it by putting a copper band around the ring to absorb the stress at the point of contact figure 13.12b). A variation on this device, shown in figure 13.12c uses a bushing to protect the ring's outer surface.
Sizing Down Gem Rings
The stone or stones are taken out and the ring shank cut, again exactly where previous joints have been made if there are any. Remember to check the inside of the band for hallmarks and engraving and to work around them. The shank is bent so the ends come together to make a tight seam, and here again it is important to file the surfaces so they make a clean joint. Failure to do this will make an imperfect soldering that will leave irregularities or pits; in the process of filing these away it is easy to make the shank too small. In the case of thin shanks, file the two butting surfaces at an angle to increase the surface contact and thereby make a stronger joint.With larger stone settings and delicate ring heads there is a danger that the head of the ring will be bent out of shape and deformed on any of the methods described above. The shanks can break off at the head of the ring or from its shoulders where the solder joints are stressed. It also happens sometimes that a thin shank is simply worn so thin it can no longer be repaired with an isolated joint.
No matter what your needs are for ring sizing, come in a we will take care of them all.
Our customers come visit our jeweler from cities in the North Bay like Sausalito, Mill Valley, Tiburon, Belvedere, Corte Madera, Larkspur, Greenbrae, San Rafael, San Anselmo, Fairfax, Novato, Petaluma, Penngrove, Cotati, Sebastopol, Rohnert Park, Santa Rosa, Sonoma, Healdsburg, Vallejo and Windsor as an example.
