A ring fits well when it is no longer felt on the finger. If in the course
of time the size of the finger changes or if the ring is to be fitted
for another wearer, a sizing of the ring is necessary. The first step
is to determine the finger size, which is done with a ring sizer, a set
of about 30 steel rings in graduated sizes, figure 13.1. If the customer
has a comfortable ring to use as a guide, its size is measured on a graduated
13.1 Ring stick and ring sizers
In Germany, ring sizes are described by the diameter of the finger hole
or inside circumference; in France and the United States, sizes measured
by a number, with higher numbers indicating larger sizes. The systems
are compared in figure 13.2.
13.2 Different measurment standards for ring sizes
Selecting a correct ring size is not as straightforward as it might at
first appear. For one thing, fingers are not round but instead have a
cross section like the first image in figure 13.3. In addition, we all
know that our fingers swell slightly in the course of the day - for some
people this can be a significant change. And of course on hot days our
fingers swell even more, while in cold weather our fingers might seem
to shrink. No wonder it's difficult to make rings fit well!
13.3 Possible measurment mistakes
a) finger form
b) ring size
c) ring with projecting pointed stone
d) non-circular shanks
There is an additional challenge for people with slim, bony fingers.
The ring must of course be large enough to slip over the knuckle, but
if there is little skin at the base of the finger the ring slips around
uncomfortably. Also, wider bands will need to be a little larger in size
than narrow ones because the wide bands trap skin beneath them. Bands
that have an opening under a stone or in some other way allow the finger
skin to swell upward can afford to be a little smaller than the same ring
without that opening.
Perhaps it would be better if all rings took the actual shape of the
finger rather than a perfect circle, but for better or worse, that is
the system that is in widest use. In the end what matters is to create
a comfortable fit, regardless of its size. Customers who insist that they
wear a specific size are condemning themselves to a poor fit. Similarly,
when a ring size is handed over as a length of string or a mark on a strip
of paper, this information must be taken only loosely since those devices
have more flexibility than the metal of the final ring.
When a ring size is checked on a ring stick, the measurement is read
at the edge that makes contact with the ring stick (figure 13.4). Though
it should not happen that the culet of a stone projects into the finger
area of a ring, it sometimes occurs, nevertheless. Such rings can be measured
on a ring stick that has a groove running along its vertical axis.
13.4 Reading the ring stick (size 52)
Sawing Rings Open Though it's not truly jewelry repair, it sometimes falls to a goldsmith
to cut away a ring that can no longer be taken off a finger. This most
often happens because an injury or illness has caused the hand to swell,
but it might be a matter of simply "growing attached" to your
The first alternative is to hold the finger under cold
water and to coat it with liquid soap. Hold the hand vertically in the
air, allowing the blood to drain from it, and try one last time to remove
the ring. If that fails the ring will need to be cut.
One solution is to use a jewelers sawframe with a coarse
blade. Insert a blade upside down so the teeth point toward the back of
the frame and slide the blade between the skin and ring shank. Cut by
sawing upward away from the hand.
A better solution is to use a ring cutter made for this
express purpose, shown here in figure 13.5. The lever pressed here with
the left thumb presses the ring up against a circular saw that is turned
with the other hand to cut through the ring. Ring forming pliers are then
used to bend the ring open enough to allow it to be slipped off.
13.5 Cutting with the ring cutter
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.
13.6 Sizing (stretching) machine
a) mode of action
b) matching profile
c) too flat a profile
d) too narrow a profile
e) too deep a profile
|13.7 Enlarging by stretching
a) ring mandrel
b) stretching mandrel (before and after stretching)
c) spring head of the enlarging mandrel (before and after stretching)
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 13.7c 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
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.
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 these methods cannot be used - most commonly because
the desired increase in size is too great - then a piece of metal must
be inserted into the shank. First examine the shank closely to see if
a solder line is already present. A shank can be lightly heated to reveal
the color difference at the solder line. If a line is present, saw the
ring open on that existing seam. It there doesn't seem to be a previous
joint, cut the ring open at the point opposite the stone, making certain
that you don't cut through any hallmarking or engraving.
13.8 Ring enlargment machine
Insert a piece of metal that perfectly matches in color
and makes a tight seam at both ends (figure 13.9). It is not critical
that the cross section of the insert match; in fact there is an advantage
to having it a little larger than the shank. After soldering the excess
is filed away to blend the pieces together. In most cases it is possible
to file the insert so it snaps into place, and while this might take some
work, the resulting invisible seam is worth the effort. When the new section
cannot be made to stay in place, use a thin piece of steel and binding
wire as shown in figure 13.10 to hold the pieces together for soldering.
13.9 Enlarging by inserting pieces. A few useful
ideas on how an inserted piece can be bound in place for soldering
are summarized in picture.
|13.10 Securing the inserted piece.
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.
Though primitive, one solution is to protect the stones
by packing them in a raw potato. Cut a hole and press the stone and mounting
into it, adding shreds of potato to bury them completely.
A variety of moldable insulating materials are commercially
available through tool and supply companies. These can be packed around
the stone like modeling clay. A variation that is best used in conjunction
with a heat insulator is shown in figure 13.11. The lid pieces (c) are
slid over the ring and attached to the box (b) which is either filled
with water or an insulating paste. The assembled unit is shown in 13.11d,
ready for soldering.
13.11 Appraratus for soldering of stone rings.
a) Prepared ring
b) Opened apparatus
c) lid of apparatus
d) closed aparatus with ring ready for soldering
It is always best if a small, very hot flame can be
used in repairs that include gemstones. The microtorch is able to heat
the metal so quickly that the heat does not have time to flow from the
joint area to the rest of the piece. The motto is to get in and out as
quickly as possible.
Allow these repairs to air cool, even if you think the
heat has not reached the stone. It is a terrible mistake to correctly
complete a repair solder without damaging a gem only to have impatience
crack the stone because of thermal shock!
- A thick shank conducts heat more quickly than a thin one.
- A silver shank conducts heat better than a gold one.
- Even heat resistant stones can crack and break due to internal structural
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.
A ring sizing machine consists of a series of conical or hemispherical
cavities and a flat anvil that is used to press the ring into them. Anneal
the ring and select an opening that is just large enough to contain the
ring, as seen in figure 13.12a. Apply some pressure to the ram, then flip
the ring over and repeat the process. Check periodically to be certain
you don't go too far, and remember to anneal periodically if you are compressing
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.
13.12 Reduction of wedding ring
a) punch and reducing plate
b) compression of copper sheath
c) reduction with plastic liner: 1. plastic liner 2. ring 3. cone-shaped
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.
In the case of massive mens' rings, it can be very difficult
or even impossible to bend the shanks down to the intended size. In such
cases it is advisable, as is shown in figure 13.13, to take out a wedge-shaped
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.
A proven method for dealing with a thin shank consists
of soldering a piece on the inside of the ring to strengthen it and to
simultaneously decrease the inside diameter (figure 13.14). Though not
nearly as good as soldering, this solution can also be achieved with a
13.13 Tightening thick-walled rings.
|13.14 Narrowing inside diameter by insertion
of inside ring