Variations and Accuracy
I received the following question in an email from a potential customer and decided to post it here as I’m sure that the answer would interest many others as well. Unfortunately, it gets a bit technical and
may bore the rest of you to tears. (The price of $39/g was several years ago, before gold soared)
The Email: (from Glen)
Just wondering exactly how much a 40 gram gold chain will cost me? I am after a 55cm curb link gold chain around the 40 gram mark give or take a couple of grams but does the $39 gram price quoted include GST? And how can there be a variation of up to 5% in prices? Can you not weigh the chain properly?
An approximately 40g chain x $39.00/gram is $1560.00 plus $15.00 postage and handling including GST.
1. Where the price is shown on the products, GST is included.
2. My scales are accurate to 0.01 grams and are calibrated with every use.
3. (The complex part) Why chains vary in weight.
The manufacturer provides me with an estimated weight of a 50cm length of each chain they produce. I base my weight calculations on this data.
The exact weight of any given chain will however vary slightly based on a number of factors:
a) The composition of the gold alloy,
b) The exact length of the chain,
c) The weight of the clasp fitted relative to the weight of the same length of chain,
d) the depth of cut with chains that are ‘diamond cut’ or ‘bevelled’.
4. (Part 3 answered in more detail)
a) 9ct gold is an alloy containing 37.5% gold by weight. The remaining 62.5% is typically a mixture of silver, copper and sometimes zinc. The proportions of silver, copper and zinc dictate the final colour of the alloy. Increasing the proportion of copper will make the gold more rose coloured. Changing the weight proportion of the metals in the alloy will also affect the volume of the alloy.
This table shows various possible alloys of gold and the resultant volume (in cc) for a 100 gram alloy.
|37.5g (1.943cc)||55g (5.238cc)||7.5g (0.839cc)||Pale Yellow||100g (8.020cc)|
|37.5g (1.943cc)||42.5g (4.048cc)||20g (2.237cc)||Yellow||100g (8.228cc)|
|37.5g (1.943cc)||31.25g (2.976cc)||31.25g (3.496cc)||Rich Yellow||100g (8.415cc)|
|37.5g (1.943cc)||20g (1.905cc)||42.5g (4.754cc)||Rose||100g (8.602cc)|
The table above shows the volume of 100g of various alloys of 9ct gold.
A chain made of rose gold will be lighter than an identical chain made of yellow gold.
Occasionally, the manufacturer varies the alloy to produce a colour of chain that suits the market. At times a very brassy yellow gold is in vogue, currently there is a lean towards a warmer, slightly reddish yellow gold.
So, variations in the alloy used to produce the chains will affect the weight of the chain.
b) It is almost impossible to make a chain of an exact length because it is made of links. A ’50cm’ chain may be anywhere between 49.5 and 50.5 cm in actual length. The discrepancy becomes more pronounced as the links increase in size. The estimates of weight by length I am given by the manufacturer are influenced by this also.
c) The weight of the clasp may be lighter or heavier than the chain it is fitted to relative to length. A shorter chain will be more affected than a longer chain in calculating the weight of the clasp.
d) Diamond cut chains have the upper and lower surfaces shaved off by a diamond cutting machine. The depth of cut can be affected by temperature, machine calibration and wear of the cutter. A slightly deeper or shallower cut will affect the overall weight of the finished chain by a very small amount. The same is true of bevelled chains.
So, there you have it, this is why all calculations are approximate.
You are buying and paying for a chain of a stated length and style. The length, width and weights are very close estimates, but not always exact.
Far more often than not, the actual weight of the chains we provide slightly exceed the estimated weight. We don’t invoice you for the extra charge, nor do we provide a refund if the chain weighs slightly less than the estimate. Please remember that you can return the chains within 7 days if you are unhappy for any reason.
When you consider our current gold price is $39.00 per gram (11/06/2011) and a jeweller is charging anywhere between $100 and $130 per gram for the same chain, from the same manufacturer, if the possibility of finding a small discrepancy in weight causes you serious concern, you are of course free to go direct to a jewellery store and pay full retail price.
They may even throw in a free gift wrapped velvet covered box.