back

Guide:
Gold jewels, Silver jewels, Diamonds

  Gold

Gold is the quintessential noble metal: being highly ductile and malleable, it is unsuited in its pure form to the production of jewels or other commonly used items. This is because the very first time it is used, it can lose its shape and any precious stones may be lost. For this reason, gold is usually combined with other metal alloys, in particular copper and/or silver. The percentage of gold present in the alloy is known as the gold content and it is expressed in  thousandths or in carats (Kt).
In its pure state (1000/1000), gold is conventionally described as being 24 Kt (carat). In Italy the gold content traditionally used for jewellery-making is 18 Kt (750/1000) but other jewels usually destined for export may have a lower gold content of 14 Kt (585/1000),12K (500/1000), (333/1000).
The gold content must be clearly labelled on every piece of jewellery and is stamped in a lozenge shape

         

The manufacturer's brand name must be stamped next to the gold content to allow identification.

Other metals combined with gold also influence its appearance and especially its colour: alloys with copper have a reddish tinge, whereas alloys with silver tend to be light yellow in colour.
The “white gold” type is produced by combining 18K (750/1000) gold with a special alloy invented in America in the 1950s known as LEKOR or rather incorrectly "American alloy". This is basically composed of nickel, zinc and copper. There have also been rather unsuccessful attempts to produce green gold and blue gold, both at 18K, which are obtained by combining pure gold with pure silver and pure gold with iron.


Gold does not tarnish, nor is it damaged by acids, except for “aqua regia”.
For the cleaning and care of jewels, see our guide section.
One final observation: if golden jewels come into contact with mercury contained in thermometers and in certain dermatological creams, this may form a light grey layer over the jewels, which can be removed by having the jewels cleaned in a jeweller's workshop.

Silver

In Italy the minimum requirement for silver alloys which can be sold in finished form is 800 /1000 or purer.
The content is labelled in an oval:

      

 

The term “800 /1000” indicates that of 1000 parts of metal, 800 are made of silver and 200 of copper alloy. 925 /1000 therefore means that of 1000 parts of metal, 925 are made of silver and only 75 of copper alloy. Silver with a purity of 925 /1000 or more is known as Sterling silver
Next to the purity mark is the manufacturer's brand name for identification.

It is worth noting that silverware can be used every day, can be washed in the dishwasher and creates no special problems. Dirty trays and plates can be washed normally but take care to avoid lemon and vinegar which can form tarnish marks.
After use, silver cutlery can easily be placed in the same drawer with steel cutlery. If it is not to be used for some time, wrap it up in cloth, tissue paper or even newspaper. You should in any case put everything into plastic bags to prevent tarnishing. Close the plastic bags with string, since elastic bands also damage silverware.
In the time, silverware does become tarnished, especially in heated rooms. To prevent tarnishing or at least to reduce it, try wiping the silverware once a week with a cloth dampened with alcohol. There are also proprietary products designed to clean silverware, the most suitable of which are creams. Follow the instructions closely and take great care to first remove all dust, which can create an abrasive paste when mixed with the cleaning cream and scratch your silverware.
 

 

Diamonds and the 4C

 

   Carat weight   

Diamonds, like other gemstones, are weighed in carats. The word “carat” dates back to ancient times when it referred to seeds of the carob tree, which are so surprisingly regular, that they were used to weigh gemstones. In 1914, the system of weights was standardised and the carat (0.20 g or 1/5 of a gramme) was adopted as a unit of weight. The carat is divided into 100 points.

   Clarity    

Owing to their natural origin, all diamonds are unique and no two are exactly alike. The greater the purity of the diamond, the greater its rarity and value. Nearly all diamonds have structural inconsistencies or small crystals of different types. These are known as “inclusions” or internal features. The number, colour, size and location of these features determines the purity of every diamond.
There are various different international classification systems to assess the internal features of the diamond. (G.I.A.,IDC, CIBJO and Scan D.N.). Currently, diamonds with no internal or external features are described as “FL”(flawless) according to the GIA system. . In all other systems, including GIA, the purest quality in terms of internal features is known as “IF” (internally flawless) or “loupe clean” (pure to the lens).

 

   Colour     

All diamonds are beautiful, irrespective of their colour. But it is also true that the less colour a diamond has, the greater its rarity and value. There are diamonds which are completely colourless but they are extremely rare (D, E, F, G and H) and most diamonds have some form of colouring (I, J, K or L) and are described as “soft white” or “slightly coloured white”. Diamonds with more colouring are classified from M to Z and are described as “coloured”. Diamonds classified beyond Z are known as “fancy” and are exceptionally rare.

 

   Cut  

Of all the four characteristics, the cutting is the only one directly influenced by human hand. The other three are all dependent on nature. The brilliance and focus of a diamond is strongly affected by the cut. This is why a skilful cutter can reveal the beauty of the gemstone.


Light characteristics of the diamond

The type of cut affects how much light will be released from the diamond.
1) In a properly-cut diamond, the light is refracted and dispersed inside, before it is reflected from one facet above the pavilion and shines out through the corona and the plate in the form of white light and multi-coloured flashes.
2) But if the pavilion is cut too deep into the diamond, some light is lost after the first internal reflection and it shines out opposite the pavilion itself.
3) And if the pavilion is too shallow, the light shines out before being reflected.

 

  Guide to Jewel-care

Jewels containing diamonds and other precious stones

Cleansing bath    

Prepare a small bowl of soapy water using a delicate liquid detergent. Gently brush the jewels in the water with a toothbrush, then place in a strainer and rinse in warm water, before drying.

 

  Cleaning in cold water.

Fill a cup with a solution of half water and half ammonia, immerse the jewel for about 30 minutes. Remove from the solution and gently brush around the mounting with the toothbrush, then immerse once again in the solution and leave it to dry on paper. There is no need to rinse.

 

   Quick immersion method.
  

Buy a proprietary jewel-cleaning liquid and follow the instructions carefully.

 

Silver jewels

Wash silver jewels in warm water, rub them with slightly damp sodium bicarbonate powder, rinse and dry.

 

Other useful tips   

-Never allow jewels to come into contact with bleach containing chlorine while you are doing housework. Although diamonds themselves will not suffer, the chlorine may attack or discolour the mounting.

-Do not wear jewels when performing arduous tasks. Even hard stones like diamonds can be damaged if struck hard along the plane of cleavage and the mounting can be damaged when subjected to rough treatment..

-Do not leave diamonds loose together with jewels in a normal jewel case, since they may scratch each other or other jewels.