One of the most common tasks jewelers are asked to perform is the sizing of rings. As with most aspects of jewelry making, there are several different approaches to resizing a ring. Many factors must be taken into account, such as the alloy of the metal, any stones set into the ring, how far up or down the ring needs to be sized, the condition of the ring, etc. This article will address several methods for sizing a ring up or down, and will include links to tools that can be used in the process.
The first step in resizing a ring is to determine the size the ring needs to be. This can be done with a ring gauge, which is a set of rings in graduated half size increments. You can also measure a different ring, which fits the intended individual comfortably, on a ring mandrel (or ring stick) to determine the correct ring size. A ring mandrel is a steel stick, graduated in thickness, and marked with ring sizes.
For a comfort fit band, or a ring made of round wire, the correct measurement can be read where the center point of the ring comes into contact with the mandrel. For a ring band made from rectangular, half-round wire, or any material that is flat on the inside of the ring, the correct measurement can be read where the edge of the ring comes into contact with the mandrel closest to the handle.
It is important to note that the width of the band can also affect the size the ring needs to be. A wider band will need to be made in a larger size because it takes up more surface area on the finger. It could necessitate being as much as a quarter to a half size larger than a thinner band would need to be on the same individual.
US ring sizes correspond to a specific diameter or circumference, which can be seen in this chart. Once the desired size is determined, the next step in the process will differ depending on if the ring needs to be sized up or down.
Generally it is not advisable to size a ring up more than two full sizes past the original size, and even this greatly depends on the thickness of the ring material, any stones present, textures or engravings on the shank, or any open gallery work.
When a plain ring band needs to be enlarged, often the simplest method is annealing and stretching. This can be done with a ring stretching tool, or with a hammer or mallet on a steel ring mandrel. Using a metal hammer will cause the ring to stretch quickly but will also leave tool marks on the surface. These tool marks, if undesirable, will then have to be filed, sanded and polished out.
If the ring material is fairly malleable, and only a slight enlargement is necessary, a wooden, rawhide, nylon, or similar mallet can be used. These mallets will not leave tool marks on the surface of the metal, but will stretch the ring much more slowly. Due to the tapered shape of the ring mandrel, it is necessary to occasionally flip the ring while working it to achieve even stretching.
A ring stretching tool is essentially a hollow cored ring mandrel made up of several splines. When a ring is placed on the ring stretching tool, the splines are spread, causing the ring to stretch. This process can be repeated to increase the size of a ring quickly and efficiently without marring the surface of the ring. Always adjust slowly or in small increments with this tool, as it is very easy to make the ring too large very quickly.
Special care should be taken with thin bands, as they are very likely to snap using this method. It is extremely important to inspect the ring carefully prior to using this method. The ring stretcher is most ideal for solid, plain bands, as any open gallery work, hollow fabrication, rings with flush-set stones, or engravings can be ruined, compressed or deformed using this tool. It is also important to note that this method will make the ring thinner. If the ring shank material is thin, or weak, these stretching methods will likely cause damage to the ring. It is important to note that any method of stretching will put stress on the metal and could result in the ring breaking.
Rings with stones set into them cannot be stretched as described above due to the pressure that would be placed onto the stone, likely causing the stone to break or fall out of its setting. There are stone-set ring enlarging tools, which depending on the design of the ring, can use roller dies to enlarge the ring without disturbing the stones. These dies place uniform pressure on the ring shank while rotating against the die, achieving even stretching without distortion.
If the ring must be increased by too many sizes, then stretching the ring is not an option. In this case, the ring can be enlarged by adding more metal to the shank. In this method, the band is cut, typically at the bottom of the ring shank, and opened up to the desired circumference. Then a bridge of metal in the same alloy is inserted to fill the gap. This bridge is soldered in place, and finished to appear seamless with the rest of the shank.
This method does not put the same kind of stress on the ring band that a hammer or a ring stretcher will, but it does add an additional solder seam, which can potentially be a weaker spot in the ring shank. If using this method, check to see if there is an existing solder seam in the ring before cutting it open. This can be done by lightly heating the metal with a torch, which will reveal a color difference at the solder joint. If a solder joint is visible, cut the ring open on that existing seam and proceed with the repair.
If the ring that is being resized has stones set into it, more care and consideration must be taken before soldering. If the stones are soft or sensitive, or contain inclusions, they should be removed prior to soldering. Stones set into silver are the most vulnerable to heat damage as silver requires more prolonged heat and conducts heat faster.
If the stones are unable to be removed, they must be protected from the heat of the torch. Some stones are less heat sensitive, but they still should be protected from the heat of the torch. There are numerous ways to do this, but generally the stones are packed in a moist or insulating material that protects them during the heating process. One such product is called Heat Shield and is a moldable clay like material that acts as a heat sink and protects stones from direct flame temperatures up to 5,000° F. This method is not recommended for soft stones. Some stones have been stabilized or treated, and even when coated with heat shield or similar products can be discolored or destroyed with even the slightest heat. It is important to be knowledgeable about the stones before attempting any repairs.
Even if the stones have not been removed prior to soldering, it is important to always double check the settings after repair work has been done.
There are multiple approaches to sizing ring bands down. If the ring is a plain band with no stones set into it, typically the most quick and efficient method is to compress it. Some ring stretching machines also have a reducing option. The reducer consists of several countersunk cavities and a flat plate that is used to press the ring into them. It is important to remember to anneal and to take special care if the ring is textured, engraved, or is made of multiple metals.
If a ring contains stones and needs to be reduced in size, generally, the stones must be taken out. This will depend on the design and how much the ring size needs to be reduced. After the stones have been removed, cut the ring shank, remove the necessary amount of material, and then re-solder the joint. Make sure to do this on the original solder seam if there is one and to take special care to make a tight fit before soldering. The ring can then be shaped and finished.
Whatever method is used to resize the ring, it is important that steps are taken to assure a clean, seamless, finished product. All solder seams and tool marks should be filed and sanded smooth, and the ring finished to its original state. Each time a ring is resized the metal is weakened. It is recommended to resize only when absolutely necessary and to avoid resizing multiple times in order to maintain the integrity of the ring.