SHOW: Rings 51


Title:      Ring.
General:    18K Gold ring set with Boulder Opal and Diamond.
Material:   18K Gold.
Gem:        Boulder Opal, Diamond.
Method:     Cast.
Finish:     Polished.
Mechanics:  Bezel Set.
Designer:   W.van Heeckeren.
Craftsman:  W.van Heeckeren.

Price:      AUS $ 8000.00.












18K GOLD.


        18K GOLD is a ternary Gold alloy consisting of:
                        750 parts/1000 Pure Gold.
                        125 parts/1000 Pure Silver.
                        125 parts/1000 Pure Copper.
 Annealing temperature: 750 degrees Celsius.
   Melting Temperature: 950 degrees Celsius.

                                                    Wal.












CASTING.


            CASTING is a method by which moulten metal is poured into a mold
                    in order to achieve the desired shape.  In the "Lost
                    Wax" method, an accurate wax model is made.  The wax
                    model is invested (put in a chrystobalite plaster),
                    after the investment has set, the wax is burned out in
                    a Kiln.  This leaves a negative cavity into which the
                    moulten metal may be poured.

                                                    Wal.











BEZEL SETTING.


        Bezel Setting is done by making a sheet metal surround (the
                bezel) for the stone.  Once the jewelry has been finished
                the stone is then set.  In setting the stone, the stone is
                placed in the bezel, and the bezel is shrunk in around the
                stone, by pushing it in little by little evenly around the
                circumference, until the metal seals tight against the
                stone. As a finishing touch a flat graver is used to bright
                cut the edge of the bezel at right angles to the plane of
                the bezel.

                                                    Wal.









Technical Data for BOULDER OPAL.


name:                   OPAL (Quartz group)
colour:                 White, gray, blue, green, orange
colour of streak:       White
mohs hardness:          5.5-6.5
specific gravity:       1.98-2.20
cleavage:               None
fracture:               Conchoidal, splintery, brittle
crystal system:         Amorphous; kidney or grape-shaped aggregates
chemical composition:   SiO2.nH2O hydrous silicon dioxide
transparency:           Transparent, opaque
refractive index:       1.44-1.46
double refraction:      None
dispersion:             None
pleochroism:            None
absorption spectrum:    Fire opal: 7000-6400, 5900-4000
fluorescence:           White:white, bluish, brownish, greenish. Black:usually none
                        Fire:greenish to brown



Technical Data for DIAMOND.


name:                          DIAMOND
colour:                        Colorless, yellow, brown, sometimes green, blue, reddish, black
colour of streak:              None possible
mohs hardness:                 10
specific gravity:              3.47 - 3.55
cleavage:                      Perfect
fracture:                      Conchoidal to splintery.
crystal system:                Isometeric ( cubic ); mainly octahedrons, also
                               rhombic dodecahedrons, cubes, twins, plates.
chemical composition:          C, crystalised carbon.
transparency:                  Transparent.
refractive index:              2.417 - 2.419
double refraction:             None, often anomalous.
dispersion:                    0.044
pleochroism:                   None.
absorption spectrum:           Colorless to yellow: 4780, 4650, 4510, 4350, 4015,
                               4230, 4155, 3900 Blue-green: ( 5370 ), 5040, ( 4980 )
fluorescence:                  Variable; Colorless and yellow: mostly blue. Brown
                               and green:  often green.