SHOW: Necklace 98

Title:      View on an inland sea
General:    This Pendant is made in 18 Karat yellow and white gold,
		and is set with a Boulder Opal, and Diamonds. There is a little
		crab in the right lower part, making off with one of the diamonds
		in one of it's claws.
		It won the 1st Prize in the 2001, Lightning Ridge Federation 2001,
		Opal Jewellery Design Awards.

Material:   18 Karat Yellow and white Gold.
Gem:        Boulder Opal.
Method:     Repoussé.
Finish:     Polished.
Mechanics:  The White Gold Screws hold the whole thing together.
Designer:   Walraven van Heeckeren.
Craftsman:  Walraven van Heeckeren.


        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.



        18K GOLD is a Gold alloy consisting of:
                        750 parts/1000 Pure Gold.
                        100 parts/1000 Pure Nickel.
                        100 parts/1000 Pure Palladium.
                         50 parts/1000 Pure Zinc
 Annealing temperature: 700 degrees Celsius.
   Melting Temperature: 1200 degrees Celsius.



              Répoussé is a method of sheet metal forming
                        where the metal is placed on a bowl of softish
                        pitch.  The metal is then hit down into the pitch
                        with smooth punches.  If the desired result needs
                        greater depth or more refining, the work may be
                        turned over and worked from the other side.  The
                        pitch supports the metal where it is not being hit,
                        and in this way three dimensional shapes of great
                        depth can be achieved.

                        Some confusion exists in the English speaking
                        world, because the word "CHASING" is used for two
                        different techniques.  In German the word for
                        chasing, is zisellieren, or chiselling. The object
                        to be decorated is placed on a quite hard "chasers
                        pitch", and is then worked with small cutting
                        punches.  the look is somewhat like engraving.


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