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Elements and Performance Criteria

  1. Prepare to cut an opal doublet or triplet
  2. Cut and polish an opal doublet or triplet
  3. Cut and polish an opal triplet commercial top
  4. Cut and polish an opal triplet non-commercial top

Required Skills

Required skills

planning and organising skills to prepare materials for cutting and polishing

problemsolving skills to identify and address common cutting and polishing problems

numeracy skills to use numerical features of machinery

technical skills to

cut and polish opals using correct technique

work safely with opalcutting equipment and materials

Required knowledge

characteristics of opal that make it suitable for use as a doublet or triplet

general principles of OHS for working in an opalcutting workshop including

complying with the safe operating procedures for each machine and materials

good housekeeping

using personal protective equipment PPE where required

materials used in doublets and triplets

processes to be used in making a doublet or triplet

Evidence Required

The evidence guide provides advice on assessment and must be read in conjunction with the performance criteria required skills and knowledge range statement and the Assessment Guidelines for the Training Package

Overview of assessment

Critical aspects for assessment and evidence required to demonstrate competency in this unit

Evidence of the ability to

cut and polish doublets and triplets from a range of types of opal using appropriate consumables and equipment and using commercial and noncommercial triplet tops to accepted industry standards

safely complete the cutting polishing and cleaning processes using equipment and consumables safely

Context of and specific resources for assessment

Assessment must ensure access to an opalcutting workshop

Method of assessment

A range of assessment methods should be used to assess practical skills and knowledge The following examples are appropriate for this unit

observation of processes and procedures

oral andor written questioning on underpinning knowledge and skills

evaluation of the final product and other methods as required

review of portfolios of evidence

review of thirdparty workplace reports of onthejob performance by candidate

Assessment methods should closely reflect workplace demands eg literacy and the needs of particular groups eg people with disabilities and people who may have literacy or numeracy difficulties such as speakers of languages other than English remote communities and those with interrupted schooling

Guidance information for assessment

Holistic assessment with other units relevant to the industry sector workplace and job role is recommended


Range Statement

The range statement relates to the unit of competency as a whole. It allows for different work environments and situations that may affect performance. Bold italicised wording, if used in the performance criteria, is detailed below. Essential operating conditions that may be present with training and assessment (depending on the work situation, needs of the candidate, accessibility of the item, and local industry and regional contexts) may also be included.

Consumables may include:

cerium or tin oxide

cleaning spirit

diamond or silicon carbide wheels #220 or #360

diamond polishing compound #2400 to #100000

diamond polishing wheels #3000 to #50000

diamond sanding wheels #280 to #1200

felt or leather buffs

silicon carbide sanding paper #180 to #600.

Equipment may include:

grinding machinery

PPE

polishing machinery

sanding machinery

saw.

Jewellers’ cutting angle requirements may include:

10º to 12º side angle

all sharp edges or acute angles be slightly rounded

flat or domed back

high overall polish and free of defects

sanded or polished back

setting edge to be straight and parallel to back

tolerance for standard millimetre sizes, 0.2mil. + or −.

Wax or adhesives for dopping may include:

any 5 minute adhesive, using aluminium dop sticks

wood glue

hot wax sticks (hot glue gun)

super glues

vacuum dopping

wax (medium to low melting).

Shape may include:

a variety of other shapes

cabochon

dome – high, medium and low

free form

rectangles.

Triplet top materials may include:

clear quartz

commercial standards size triplet tops

glass, plain or plate

lead crystal glass

material of the triplet top should be disclosed

synthetic spinel, corundum and topaz.