This long page is designed to give you general and specific information and advice about materials & products that jewellers sell, together with general advice about the benefits of cleaning your jewellery regularly.
Topics covered
CARAT - QUARTZ - Moh's Scale of Hardness - HARDNESS versus BRITTLESNESS - WATCH WATER RESISTANCE - CHLORINATED WATER - WEAR & TEAR - CLEANING JEWELLERY - INSURANCE
CARAT
The name has two different meanings but derive from the same root.
A carat as a measurement of weight, it equates to 0.2gram, thus 5 carats is the equivalent of1 gram. The carat is divided onto 100th parts which are called points. A point is therefore the equivalent of .002gram. As gemstones are sold in carat weights, and the price can be in hundreds of pounds per carat, each point can be material in pounds sterling. The weight system that incorporates carats is called the TROY system.
A carat is also a proportion scale, as in 22 carat gold [22ct, 22kt.]. Here the numeral indicates how many grams of gold are included in a total weight of 24 grams. This is now also expressed in parts per thousand:
9ct gold = 375 14ct gold = 585 18ct gold = 750 22ct gold = 916
The origin of the word CARAT is a corruption of the name Carob. The Carob Bean grows as a fruit on trees around the Mediterranean, you can see them looking like shrivelled brown broad bean pods. Inside is one of nature's wonders, for the Carob bean is remarkably regular, take 100 and they will all weight the same. This fact was recognised early in history and the carob bean accepted as a unit of weight. The carob bean is also used as a substitute for cocoa.
Associated Page: British Hallmarks
QUARTZ
Quartz is the name of a silica based mineral, SiO2. It is common throughout the world and is normally seen as sand, or as a constituent in many rocks.There is a whole series of Quartz gemstones ranging from the purest form with no contaminants called Rock Crystal. The presence of mineral salts within the host quartz can cause other colours to be seen Amethyst and Citrine being best known. The mineral may form from hot underground water in a vapour coming into contact with other materials and leaching them away but retaining their form as in Tigers Eye, which is a replacement of Asbestos. Moss Agate, Jasper, Cornelian and Bloodstone are a few more of the many gem and mineral forms of Quartz.
Quartz has the interesting property of oscillating at regular frequencies when excited by electricity. This phenomenon is used when shaping a quartz crystal for a timepiece. The oscillations are trimmed to 32,768 times per second. By digitally separating each pulse per second it is possible to reduce the pulses through sixteen steps to a regular 1 second pulse of great accuracy. This is far more accurate that the 5 beats per second of a conventional watch. Commonly this will give accuracy for a quartz watch of better than 2 minutes per year, and some Seiko models promise 20 seconds per year.
Associated Sections: Watches
Emerald.
I was fortunate to visit the Belmont Emerald Mine in Brazil in 2005 with Gem-A. There we saw that this remarkable gem in its birthplace. The Mineral family that includes Emerald is the Beryls; the pink is called Morganite, the pale greenish blue is Aquamarine, and the Golden Beryl is termed Heliodor - there are others including some alternative greens. What makes Emerald that particular grass green is the presence of Chromium as a trace element. As explained to us - with much enthusiasm by the Gem-A's senior education man Doug Garrod - Beryllium and Chromium do not occour in together, it needs an iintrusion of Beryllium rich magma to come into contact with a sedimentary rock containing Chromium, and there at the contact zone is the birthplace of Emerald. Even then there is no assurance that the green crstalline material will be suitable as a gem. We saw in the intrusion native gold too.While there are favoured localities for Emerald, there is a strong suggestion that many of the current colombian offerings may have found their to market from The Valley Esmaraldes in Brazil.
HARDNESS
Moh's Scale of Hardness is a useful way to compare gemstones hardness against comparison minerals. The scale has no scientific scale, it is not linear, geometric or logarithm based. It has ten points of reference which progressively are more resistant to abrasion, scratching.
1. Talc 2. Gypsum 3. Calcite 4. Fluorspar 5 Apatite
6 Feldspar 7 Quartz 8. Topaz 9. Corundum 10. Diamond.
Gemstones softer that 7 should be worn with care and are not suitable for everyday wear unless you have servants, and do no work or shopping. They may have great beauty, and should be worn when you want to feel very beautiful, currently we use the term Coulture Jewellery. Remember silica is the common material it is hardness 7and will scratch anything with a lower resistance..
Gemstones in the 7 to 8 range are suitable for regular smart wear, but may be scratched or otherwise damaged if in contact with stone or steel or other harder materials.
Gemstones with the range 8 to 9 are hard to scratch, but a diamond rubbed gently against them (as in a jewel box) will scratch them easily.
10 Diamond - there is nothing remotely as hard as a diamond. Indeed there are directional differences in hardness within Diamond, and it is that difference that allows them to be shaped and faceted.
Some Gem Hardness Guides within Moh's Scale
Amber 2½ Aquamarine 7½ Diamond 10 Diopside 5 Emerald 7½ Garnet (some) 6½
Haematite 6 Iolite 7 Moonstone 6 Jadeite 7 Lapis Lazuli 5½ Malachite 4
Opal 6 Pearl 3½ Peridot 6½ Quartz 7 Ruby 9 Sapphire 9
Spinel 8 Tanzanite 6½ Topaz 8 Tourmaline 7 Turquoise 6 Zircon 6½-7½
BRITTLENESS & CLEAVAGE
These are other physical characteristics of minerals. Diamond, which is very hard, can be split into parts with a single blow. That blow must be perfectly aligned to the original crystal face, and splits the diamond through is growing plane. It is a skilled job to do in the workshop that can rarely happen when the stone is in wear. The chance is 1 in xty million hits - but then so is the chance of winning the lottery.
Gemstone such as Tourmaline which grows in long pencil like crystals can part across the length. This characteristic can mean a sharp tap can cause the stone to split [part] and then fall out of a setting in two pieces. The beauty of the gem makes this risk worthwhile. Fortunately underwriters haven't got the time or expertise to start making actuarial lists of all gems, but insurance is a great thing, to cover the natural characteristics of gemstones.
Enamelling is a process of raising layers of glass, all enamels will chip and break if not cheerished.
WATER RESISTANCE and other WATCH CHARACTERISTICS
Most w atchmakers have yet to make a great leap in customer friendly terminology***. You need to think about what extremes you are likely to encounter when wearing your watch. If like me you put it on and do everything in it, from swimming to rebuilding dry stone walls then the specification must be very high and still it will get scratched and end up looking tatty over months and years.
Wash your watch carefully in fresh water if it has been in salt water or chlorinated water.
The scale that watchmakers use is a technical one, the amount of pressure that will be resisted, thus 3bar, 10 bar & 20 bar are made when 1 bar is the equivalent of atmospheric pressure. These are then translated into the equivalent of water pressure expressed in metres. But this is STATIC WATER PRESSURE, and when we are swimming we are not static. Similarly if water from the garden hose hits your watch the water is not static. Movement greatly increases the pressure. The pressure of water behind a person diving into a pool in the first inch is much greater than the 3 or 4 metre static depth of sitting on the pool floor!
Water is taken as regular water, not heated water, and certainly not water vapour as in the steam room. It is H2O, not water with soap that is tested, the soap intended to reach inside the micro pores to clean everything can over months penetrate the seals, which is why along with sweat penetration that watchmakers recommend regular replacement of the seals.
Standard advice is that for regular swimming use you should tell the retailer you swim and look for at least 5 bar water resistance. If you scuba dive look for 10bar water resistance, and if you use an aqualung you must expect 20 bar pressure.
For professional divers the problems of Helium build up may present themselves. Some watches have had the glass pop off with the differential pressure, which is why Omega incorporates a Helium Escape Valve in some Seamaster Professional watches. Saves your watch getting the bends.
If you use a pressure hose or a power shower - take your watch off, accidents do happen, often un-noticed until hours later the watch glass mists up.
If your watch gets water in it - the watch will probably rust inside. Get it back to the manufacturer as quickly as you can for a service if the watch is worth spending money on. Send it direct by special delivery or return it through your jeweller/watch retailer for them to return.
*** Update June 2005. Rotary watches have taken the problem on board and have introduced a whole new concept - the Dolphin Marque. These are Lady's and men's regular dress watches that can swim and play all day. For a watch priced from £75 upwards this is a remarkable change. Come and see a lady's dress watch in a fishbowl. Naturally the water resistance needs to be maintained to when the battery needs replacing the watch is returned to Rotary for replacement cells, seals and testing. The charge is £32.
SWIMMING & GOLD
Apart from watches, swimming in a chlorinated pool can damage jewellery. The chlorine attacks the gold solder. Weeks later - sometimes months later a tiny stress will cause the solder to part.
Typically this is seen as a ring shank splitting at the back, as chains breaking and becoming brittle, and earrings just becoming lost.
We regularly see an upsurge in this type of damage after the summer holidays when people have been using the heavily chlorinated pools of the Mediterranean and Americas.
WEAR & TEAR SWEAT AND TOIL
Brooches are wonderful they rarely rub against other materials, and they last longer than other forms of jewellery. They are removed from dirt and sweat.
Rings and bracelets. Hand jewellery gets more knocks than any other form of jewellery. Hands come into contact with more acidic and alkaline solutions than other forms of jewellery. It is therefore sensible to use the hardest gemstones in the strongest settings. If you fall in love with a turquoise and pearl dress ring then expect to be very careful using it or expect the pearls to exfoliate and become loose in their settings and for the turquoise to become rusty - there is a trace of iron in turquoise. Your hands get knocked dozens of times a day, and rings standing proud as they do will get more knocks, most of which you will not feel. If you are doing jobs around the house be prepared to take your dress rings off and put them in a safe place.
The most hazardous environment for rings and bracelets today is the Supermarket. I can't count the number of insurance claims I have dealt with where the wearer has been to the supermarket, and filled the trolley, then pushed it to the checkout and then plunged their hands into a closely barred steel wire frame, lifted awkward tins and packages up brushing the outside of the hand against the steel. The shopping is then put into awkward large boxes and these barely squeeze into the trolley, they have to be lifted out by cramming the hand between carton and wire, and the great weight lifted up into the back of the car. By now the safety chains are broken or claws have been pulled, the stone precariously balanced ready to fall out at the trolley park, or on the way back to the car, or when the shopping is unloaded.
I genuinely look forward to the day when home deliveries again become common place - I would willing sacrifice the substantial repair turnover to avoid seeing people either distressed that they have lost a treasured possession or as is becoming common - looking for someone else to blame for their own actions.
Clothing.
Synthetic fibres and denim are not jewellery friendly. The strength of even a few threads can be stronger than a gold claw. The battle is an unequal one and the jewellery will be damaged, and the wearer probably unaware that there has been a fight. Denim was originally worn as work-wear, able to withstand horse riding and ranch chores. A jewellery workshop could make an abrasive to polish down gold and silver from denim, indeed many buffer mops are softer than denim. Claw set jewellery and spiky charms may damage most easily.
Perspiration
This should be removed from all jewellery on a regular basis. A row of pearls can end up with a film of dirt and sweat between the pearls were they are not polished by the wearers skin, it detracts from the appearance and can cause damage to the pearl, the two strands of silk that hold the pearls can also become stained, often a greenish hue.
Watch backs can become a harbour for dirt that eventually causes an irritation or eczema.
Earrings, particularly post and scrolls build-up layers of dead skin and sweat if not regularly cleaned. This can lead to infection of the hole, or discoloration of some carbonate based gems such as pearls, and malachite.
Chain. The buildup of dirt can lead to the formation of a grinding paste that accelerates wear between links of neckchains and bracelets.
CLEANING DIAMONDS & GEMSTONES
It is an interesting fact that at the diamond mines they recover some of the diamonds by passing the slurry of water, rock and diamonds over a grease table, the water and the rock wash away, but the diamonds stick to the grease.
The same happens in reverse in the kitchen, the water runs over and the grease sticks to the diamonds. This quickly builds up in a germ haven. Just regular soaking for three minutes in warm water with a washing up liquid drop will keep Diamonds bright and sparkling. Check on the right ways to keep jewellery clean at the time of purchase.
In the shop we use an ultra sonic cleaner with an ammonia solution that is suited to cleaning most jewellery, but don't try this at home we have seen some horrid disasters. Gin is a very expensive option, and we would suggest Haggerty's jewel clean bottles with a brush for quartz, sapphires and diamond cleaning. Don't use Haggerty's Silver clean on gemstones unless specifically advised. Do use a polishing cloth, but be gentle near stone settings.
As thirty years have passed I can tell about a woman who had a citrine ring repaired in Selfridges where I trained, the customer complained on collection of the ring being sized that we had switched the stone. She would not be placated or assured that the stone was original, and that we wouldn't dream of switching any stone. After tears and trauma and a growing crowd the canny old buyer, who had risen from the workbench, intervened and disappeared for two minutes into the foodhall, above which at that time were the workshops. He returned with a very different looking stone which the customer grabbed and claimed for her own. He gently explained it was the same stone, only now it had a liberal coating of butter and flour, mixed with cigarette ash, just as she had left it.
Insurance
I strongly urge you to insure your valuables. I know that the sentiment can never be replaced, but you can continue to enjoy the benefits of looking and feeling good that the original jewellery gave to you.
Have the jewellery split into three groups, those items over the specified floor limit of the policy - those that need individually itemising. Typically that will be items over either £500 or £1000.
The next group should include valuables in excess of your excess, typically £100.
These two groups should be professionally appraised (examined) and valued. The total of group two will form the majority of your unspecified pool.
The third group, items under your excess may still be the subject of a claim if more than one item is lost in one incident. These we can give a less detailed description, for which you will pay less.
Do remember that even though your insurer may not require a valuation to underwrite the policy they probably will require some documentary evidence should a claim materialise.
