How is a Ring Sized
Probably the most common jewelry repair is ring sizing. A size change of as little as 1/4 of a size, roughly .5mm in length, can greatly change the way a ring feels on the finger. It can go from too tight to too loose in just that small of a change. As people lose or gain weight, age, and experience other changes, their rings will need to be adjusted to allow them to be worn comfortably, and securely.
In this article, we hope to show you the basics of sizing a simply gold band up just 3/4 of a size. This is a very common size change for people looking to have their jewelry fit just a little bit better, yet it's a small enough change that we don't have to worry about other issues that come into play when going up or down more sizes or when dealing with complex rings with channel or bar set stones, or delicate Filigree work.
As with all of our jobs, the first thing we need to do is make sure we have the tools we will be needing. We'll need a jeweler's saw, several hammers, a collection of files, our Foredoom hand piece, the ever present calipers, and of course the ring and some gold sizing stock. Also needed, but not in view, are the torch, several jars of chemicals, and the gold solder. Once we are sure that all of the tools are ready, it's time to begin.
The first thing we do when working on any jewelry piece is to make sure that it is very clean. This can mean hours in an ultrasonic cleaner, dipping in a mild acid, or even more aggressive means. Contaminates on any jewelry surface that is to be soldered or welded will keep you from having a solid and secure joint. While working on jewelry can be a messy process, keeping everything as clean as possible is very important.
Once the ring is clean we need to verify it's current size. This ring is slightly larger than 8 3/4. Since we will be sizing up to 9 1/2 we now know how much metal we will need. When sizing up this isn't quite as important as it is when sizing down. If you don't know where you are starting, you'll never be able to get where you want to be. Next we measure the shank of the ring. This ring is slightly over 1mm thick and slightly over 2mm wide at the bottom of the shank where we will be doing the sizing. We need this measurement so that we can choose the proper size of sizing stock.
Sizing stock comes in several standard sizes and all karat weights. In this case I chose a 14k yellow piece of stock that is 2.5mm wide and 1.5mm thick. We always want to be slightly larger than the shank we are sizing so that we can file the added metal down and blend it in with the ring so that it appears original.
Next we secure the ring in a ring holder. Ring holders are wood and have leather pads on them to hold the rings securely without marring the surface. Once secure we take our jeweler's saw, cut a straight line through the ring at the bottom of the shank at the thinnest and narrowest point. Once cut we slide the ring back onto the ring mandrel, we pull it down until it's the size we want. At this point, depending on how much you are sizing the ring, you may pull it slightly larger than needed and tap it lightly with a rawhide mallet to help it maintain the new size without adding any metal at all. Gold has some metal memory and it tries to return to it's original shape, so tapping it into a larger size now makes it easier to solder and size later.
Once we know how many sizes we will be going up on this ring, we can set our dividers to the size we need and mark our sizing stock for cutting. You can either take the measurement off of the ring mandrel, or you can measure the gap in the ring itself when it is slid onto the mandrel to the right size. Once we know the size I make my sizing stock piece about 1/4 size too small. You'll see why in a few pictures.
Now we need to put the sizing stock into the ring. Since all of our saw cuts are square, and the ring will by under some tension while we stretch it to take the new piece of gold, we need to do something to force the ring to hold onto the gold while it is soldered in place. If we don't, the gold piece will simply squirt out of the ring and we'll have to crawl on the floor looking for it, or cut a new piece wasting good gold. The solution to this problem is pretty simple. We file a small bevel into the ring shank to make the edges pointed. Then we file the sizing stock into a V shape and now the two pieces will mate together and the ring will hold onto the gold piece for us so that we can solder safely. Once the gold is added to the ring, you can see how the two pieces meet up and how the new piece is slightly larger than the original shank.
Now the fun part, fire! First we coat the ring in a solution of Borax and alcohol and then burn off the alcohol. This coats the ring in a layer of borax that will protect any diamonds that are set in it from burning by keeping oxygen in the air from getting to them, and will also protect the gold from getting fire scale. Fire scale is a byproduct of heating metal and can damage the metal to the point where the entire piece may need to be refinished to return it to it's original look. Once coated we take a torch and heat the area we want to solder. When the gold approaches the proper temperature we get the gold solder ready and place it on the seam to be soldered. I prefer to set a small ball of solder on the seam then heat it, while others like to heat the gold to the point that the solder will melt the instant it touches the ring. It's a style choice. After both sides of the joint have been soldered the ring needs to be cleaned again before it can be filed and finished.
Now clean, the first step is to file and smooth the inside of the ring. The inside of the ring needs to be as close to perfect before we can finish the sizing and then finish the outside of the ring. This last image shows why we left the sizing stock slightly too small for the sizing. With a small hammer we then tap the ring up to exactly the size we wanted. Each tap makes the ring slightly larger and we can work up to the proper size without worrying about going to far as can happen with a sizing piece cut to exactly the right size, or accidentally taking too much metal off of the inside of the ring.
And here we have the finished ring. After hammering it up the last 1/4 size and then filing and polishing it back to it's original shine, you can see no seam lines or marks on the ring to show that it had ever been modified. And it's even the right size!