Assaying Silver

Unlike gold, silver is assayed using a

process known as “potentiometric titration”.

A sample will be scraped from the item

to be assayed which weighs between

50 and 250 milligrams. The sample is

then weighed using a highly accurate

balance and dissolved in nitric acid.

In order to determine the silver content,

potassium chloride is added to the

sample and the electrical conductivity

of the solution is tested until the point

that the “titration” is complete and all of

the silver has become silver chloride. The

amount of potassium chloride needed to

get to this point indicates the amount

of silver that was in the original sample.   localhost/750jewellery.com/httpdocs

What is the difference between 9 carat and 18 carat gold?

What is the difference between 9 carat and 18 carat gold?

18 carat gold jewellery is made up of 750 parts pure gold out of 1000 parts, the remaining 250 parts being made up of other metals, mainly copper and silver. 9 carat gold jewellery is made up of 375 parts pure gold out of 1000 parts, the remaining 625 parts is made up of other metals such as silver, nickel, palladium and zinc. So 9 carat gold is just over 1/3rd gold content, whereas, 18 carat gold has ¾ pure gold content. So for example, say you have in front of you a mobile phone, if your phone was made of 9ct Gold, one third of the phone would be pure 24ct gold, the remaining two thirds would be made up of alloys (silver, nickel, palladium & zinc) If your mobile phone was made of 18ct Gold, two thirds of the phone would be pure 24ct gold with only one third being made of alloys – hence the difference in price between the two items.

18 carat gold is practically completely resistant to chemical attack in normal use, whereas 9 carat gold is much less resistant. Be aware that 9 carat gold will tarnish, go dull, bleach some fabrics and sometimes turn black from chemicals in the atmosphere, perspiration and household cleaners. That is why sometimes some people have an allergic reaction to wearing 9 carat gold, leaving black or green marks on the skin. This is a chemical reaction to the metal alloys, not the gold, usually the nickel in 9 carat gold reacting with the skin. Nickel is the most common cause of dermatitis through allergic reactions when in contact with the skin.

Nickel is not present in 18 carat gold. Our 750jewellery 18 carat gold items are nickel safe and our policy is to use only ’white gold’ alloys containing palladium.

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Palladium

Palladium is one of the platinum group metals but is considered a precious metal in its own right. Palladium is naturally white which means that there is no need for rhodium plating. Palladium is more precious than silver. It is less dense than platinum, being nearly half the weight, so larger necklaces and bracelets can be made, capable of bearing larger gemstones with minimal gain in overall weight. For the same reason, palladium is considered to be a good choice for earrings although unlike platinum it is not hypoallergenic. It is often recommended as a good alternative to 9Kt white gold for male bridal consumers due to it never needing re-plating.

(with thanks to CIJBO)

 

Freshwater Pearls

Did you know that most pearls used to come from saltwater molluscs? Freshwater pearls were rarer and less suitable for items of jewellery. For one thing they’re less round and they don’t have as high a lustre as certain types of saltwater pearls. With the advent of cultured pearls however, freshwater pearls have found a new lease of life. Their odd shapes and colours are increasingly popular because jewellery design allows for more variety than ever before.

Saltwater pearls are cultured differently to freshwater pearls. You may know that pearls are formed when a foreign object is inserted into the pearl, for example a bead. Nacre grows around the bead to form a pearl. In freshwater pearls instead of a bead, a small piece of tissue is inserted instead and the nacre grows around this. The tissue isn’t round and therefore the resulting bead is an irregular shape.

Even though freshwater pearls are irregular that doesn’t mean they’re of a lower quality. Because they’re completely made of nacre and don’t have a bead in the middle, they are actually very durable.

There’s no set way of grading pearls although many retailers use a common system. To a large extent it comes down to personal taste. You may prefer your jewellery in a classic design with round or teardrop shaped white pearls, or you may prefer a necklace made of irregular and multi-coloured pearls. The choice is endless and because there are so many different varieties of pearls, you’re sure to find something you like.

Gold – Always a Good Investment

We may be in the middle of a credit crunch, but the gold jewellery market is buoyant with gold a better investement than ever.

As the value of currencies fluctuates, more and more people are putting their money into gold. It has a special status as a sort of universal currency – valued the world over, gold is a steady investment and unlike numbers in a bank account, you always know where your money is!

Of course if you invest in gold you’ll only invest in the best – at 750 we only sell 18 carat gold jewellery so we understand the need for timeless quality. Take a look at our collection to find out more.

Pearls – A Brief History

Pearls have been valued for their beauty and rarity from ancient times, with texts from as far back as over 2000 BC detailing their use in China as gifts to and from Royalty. When explorers first found America, the native population used pearls in their jewellery and as items of trade. The Romans valued them so highly that they tried to ensure only the very highest echelons of society were allowed to wear them. It seems that almost everywhere in the world where pearls were discovered, they were valued as gemstones and items of worth.

So why were pearls so highly valued? Well their rarity probably had a lot to do with it. Pearls grew in nature and had to be found by divers or fishermen, and even if you found a mollusc that produced a pearl, the pearl wasn’t necessarily round or smooth. It might be full of flaws and an odd shape making it difficult to use in jewellery. The sheer time and effort that gathering pearls took meant that only people of status could afford them.

The natural lustre of pearls also certainly contributed to their popularity – there’s simply nothing in nature quite like the colour and shine of a pearl and it’s no wonder that ancient people coveted them.

Why are pearls so affordable today? Natural pearls are actually still very rare and expensive – even more so than ever before in fact. Over-fishing and pollution have wiped out much of the mollusc population so places where pearls used to be found don’t produce them any more. The pearls that everyone uses in their jewellery are actually cultured pearls. Not quite man-made, these come from molluscs that are specially bred, and the process of pearl formation is physically triggered by people. The supply is therefore predictable and steady, and the pearls that are produced have a uniform colour and size so it’s a lot easier to match them for jewellery.

Having said this, there are still varying qualities of pearl even in the cultured pearl market. Some have very thin layers of nacre (the shiny surface) and are of a lower quality than pearls with a thick nacre layer. We only source the best cultured pearls from reputable suppliers – the better quality the pearl the longer it will last if you take care of it, so the better the investment.

Pearl Grading

Unlike for diamonds, there’s no industry-wide system of grading pears. This means that it can be difficult for buyers to understand exactly what quality of pearl they’re getting. When it comes to pearl jewellery there are a lot of different considerations including the size and the matching of all the pearls that make up the piece (for example a necklace). To some extent individual quality is less important than the overall effect. However, sellers do have systems for grading the flaws, lustre and nacre – the three most important aspects of a pearl.

The two main grading systems are called the AAA-A system (usually used by sellers) and the A-D system (usually used by producers). The highest quality pearls (AAA and A respectively) have the least flaws and the highest lustre, whereas the lowest quality (A and D respectively) have the most flaws and the lowest lustre. Pearls with many flaws are considered unfit for use in jewellery.

Nacre is the outer surface of the pearl and the thickness of this nacre determines how durable a pearl is. Looked after properly pearls can last for generations but a thick layer of nacre helps – Tahitian pearls in fact aren’t even sold if the nacre is less than 0.8 of a milimetre.

Tennis Bracelets

What do diamonds have to do with tennis? According to Wikipedia, in 1987 champion tennis player Chris Evert was wearing a thin, diamond bracelet made by famous jeweller George Bedewi. During the match the braclet snapped, and play was halted so that Evert could find the diamonds. From then on, that style of bracelet gained the name ‘tennis bracelet’ and became increasingly popular.

What a great story! We’ve got our own special diamond tennis bracelet letting you save almost £1000 on the RRP.

Selling Scrap Gold

Selling your scrap gold is a fantastic way to make some extra cash. Whether you have a ring you never wear or a necklace that’s become tangled and broken, you can exchange it for money quickly and easily. You might even want to invest in some new jewellery with the proceeds.

At 750 we buy gold jewellery of all carat values. The price we pay depends on the gold content, the weight of the item, and the price of gold on the day we receive it. An 18ct gold ring will be worth more than a 9ct ring of the same weight, for example.

Gold is increasingly seen as a good investment because the value has gone up over recent years, so your unwanted jewellery might be worth more than you think. At the same time, the price of gold fluctuates day to day, but we do publish a to the sort of price you can expect.

There’s no obligation to accept our quote for your scrap gold, but should you be happy with the price we’ll send payment straight away.