Basic Characteristics:
      Hardness: 10 (Mohs hardness scale)
      Specific weight: approx 3.5 grams per cubic centimeter
      Main constituent: carbon
      Color: Colorless, yellow, brown, black, blue, red, green
      Main producing countries: South-Africa, Russia

   How to cut diamonds:
      Today with discs sintered with diamond dust, formerly splitted with a wedge,
      a diamond can be split in a special direction in two pieces.
      But this was sometimes complicated when the split didn´t happen as predicted.

   How to smooth and polish diamonds:
      With diamond dust - this works because diamond has different hardness in different
      directions. This way within diamond dust, where orientation of the diamond particles is
      randomly and every hardness grade is there with about equal distribution,
      the hardest particles smooth and polish the stone. 

   Brillant:
      A brilliant is a special cut of an diamond, and it is convenient to say "brilliant" instead
      of "diamond in brilliant cut".
      This cut has 56 facettes, or 57 with the Kalette, which
      can exist as a small plane on the point of the lower part of the stone.
      In ideal proportion the overall height of the stone is approx. 64 percent of its diameter.
      Be careful that in this way of measuring it is possible that a too flat lower part and too
      high upper part would give a good overall result. So look at the right proportion of
      lower and upper part.

      Classification of Brillants:

         Color from very good to very bad:
            River
            Top Wesselton
            Wesselton
            Top Crystal
            Crystal
            Top Cape
            Cape
            Light Yellow
            Yellow

         Clearity from very good to very bad:
            if - Internally flawless 
            vvs - Very very small inclusions
            vs -  Very small inclusions
            si - Small inclusions
            P1 - 1 st pique
            P2 - 2 nd pique
            P3 - 3 rd pique

         Weight:
            Unit of measure is carat, 5 Carats are 1 Gram

   Approximate Weight of Brilliants from Diameter:
         1 mm - 0.003 ct
         2 mm - 0.03 ct
         3 mm - 0.09 ct
         4 mm - 0.22 ct
         5 mm - 0.43 ct
         6 mm - 0.74 ct
         7 mm - 1.17 ct
         8 mm - 1.63 ct
         9 mm - 2.49 ct
       10 mm - 3.42 ct

   Note that an ideal height is assumed and these are only approximate values.
   Weight can differ from this values, because of differences in thickness
   of rondiste and height.
   Generally diamonds should be put on a scale for determination of weight.
 

   Visit also De Beers, where you can find further information.
 

Emerald

   Basic Characteristics:
      Hardness: 7.5 - 8 (Mohs hardness scale)
      Specific weight: approx 2.7 grams per cubic centimeter
      Main constituent: Aluminium - Beryllium - Silicate
      Color: Green in different shades
      Main producing countries: Columbia, South-Africa

   The Emerald has a very special green, so "emerald-green" is an independent color,
   the value of the stone is very much depending on the type and intensity of the green.
   If the color is very good, the value of the stone can be higher than this of an
   equal-sized diamond.
   Further possible are enclosures in the stone, called "jardin" from French "garden",
   which figuratively describes the appearance of these enclosures. The best qualities
   are clear, but small enclosures do not count as faults, in contrary they can prove the
   authenticity of the stone.
 

Gold

   Basic Characteristics:
      Melting point: 1063 degrees Celsius
      Specific weight: 19.3 grams per cubic centimeter

   Gold is seldomly processed in pure condition in juwel industry, mostly it is alloyed with other
   metals, i.e. copper, silver, palladium (in former times also nickel).
   Copper, silver, and gold alloyed together result in yellow gold, red gold or slight green gold,
   alloys with gold, copper and palladium result in white-gold.
   Be carefull, white-gold alloyed with nickel can cause allergic reactions, therefore
   you should prefere palladium white-gold (palladium belongs to the platinum-metals).
   Seldomly there are also alloys with gold and other metals, in case of aluminium the result
   is light blue gold, but this is difficult to handle and has presently only a small market.

   The common used alloys are:
      18 karat equiv. 750/000
      14 karat equiv. 585/000
        8 karat equiv. 333/000

   From these 18 karat is the most valuable and 8 karat is the cheapest. 8 karat is mostly
   used from juwel-factorys to reduce material-costs, it is also mechanically,
   chemically and in color not very good, therfore often electrically overcoated with a thin
   layer of higher alloyed gold to disguise its bad color.
   14 or 18 karat gold is from good quality, whereby 14 karat is a little harder and 18 karat
   has the better color.

   Note that there are other alloys that differ in fine metal percentages from the above ones.
   As long as the fine metal share is higher or equal than stamped there is no problem.
   (Please note also that this is German law, other countries may have different laws)
 

Making Juwels

   All starts with either casted gold or already prepared material.
   Casted gold is manufactured in form of sticks or plates, this can further be processed with a
   roller to smaller sticks, wire or sheets.
   Prepared material also are available as sheet, bar, wire, tube, and so on, even with special
   cross-sections.
   These materials are formed to the appropriate parts with hammer, plier or saw, then the
   parts are soldered together. Now the piece can be filed, milled, grinded.
   If stones are designated then the stone bearings are cut und then the stones are set.
   After all that work the piece has to be polished and finished.

   Please note that joining can be done through welding with gas,  laser, electricity, too.
   Parts that are very difficult to create can or must be manufactured with casting.
   Prior to that, a model for the cast has to be created from wax, wood, metal, or
   some material suitable.
   It is possible to create complete juwels through casting, most factory-produced juwels
   are done that way.
   The working cycles are often not so straight as described above, rather often repeating
   and mixed. The only thing that is always the same: polishing, apply a finish and
   cleaning at the end.
 

Platinum

   Basic Characteristics:
      Melting point: 1774 degrees Celsius
      Specific weight: 21.45 grams per cubic centimeter

   Platinum is a very valuable metal, has a steel-like color and is harder to process than gold
   or silver. Platin processed in juwels is mainly an 960/000 alloy from platinum with cooper,
   but there are other alloys with different platin metals, which are Ruthenium, Rhodium,
   Palladium, Osmium, and Iridium. Some alloys have only technical use, some also have
   use in juwels where a special stability and hardness is desired. Platin-Iridium is such an alloy.
   To reach stable connections it is preferable to weld platin, this can be done with an hydrogene-
   oxygene flame or with a laser. Soldering is possible but not recommended.
   For melting the combination of hydrogene-oxygene or a high frequency induction oven has to
   be used.
   The finish for platinum ist often matte which can be done by treatment with fine sand or
   glaspearls (0.05 - 0.1 mm diam.), polished it has nice color too.
 

Sapphire
   Basic Characteristics:
      Hardness: 9 (Mohs hardness scale)
      Specific weight: approx 4 grams per cubic centimeter
      Main constituent: Aluminium Oxyd
      Color: Colorless, blue in different intensities and shades, violett, pink, green, orange, yellow
      Main producing countries: Australia, Ceylon, Thailand, Birma

   The sapphire is a common used precious stone, from all colors the blue one is
   mostly known. Within the blue color there are wide variations in intensity and color,
   whereby the color that resembles the blue of the cornflower is the most precious.
   The pink or pale red variations are assigned to the sapphire, where red ones are assigned
   as ruby.
 

Silver

   Basic Characteristics:
      Melting point: 960.85 degrees Celsius
      Specific weight: 10.5 grams per cubic centimeter

   Silver is an easy to process material, often an alloy of 925/000 is in use. This is called
   "Sterling Silver". Silver is used for tableware or inexpensive juwels. Currently the silver price
    is very low in comparision with other precious metals, so the material-cost of  a
   heavier / massive juwel is very reasonable.
 

Stonesetting

   The main purpose of stone-setting is to give a stone a safe support in a juwel. The
   technique to do this varies from type to type of the setting, but in principle this can be
   achieved by putting material from the work-piece over the outer edge of the stone.
   Important is to use enough material to give a secure hold and use as little material
   as possible, because too much makes the stone optically smaller or in the case
   of diamonds the reflected light gets lost at a certain amount and the stone looks dark
   or looses of its sparkle.
   One exeption of the above said is the so-called "hidden-setting" where small wires
   running in channels cutted under the outer edges of the stones hold them in place.

   In general the quality of the stone-setting work can push up a juwel or to bring it down.
 

Ruby

   Basic Characteristics:
      Hardness: 9 (Mohs hardness scale)
      Specific weight: approx 4 grams per cubic centimeter
      Main constituent: Aluminium Oxyd
      Color: Red in different intensities and shades
      Main producing countries: Tansania, Ceylon, Thailand, Birma

   The ruby is also well known like the sapphire is, the difference that makes a sapphire to a
   ruby is the different color-giving component in the stone. The chemical and mechanical
   data are identical.
   From the sapphire group,  when comparing identical qualities, the ruby is the
   more precious and expensive.
 
 
 

This is only a small overview, there are a lot more interesting things, but we hope this
little information has some use for you.