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Elements and Performance Criteria

Required Skills

Required skills

use of appropriate equipment

ability to select the appropriate consumables

Required knowledge

characteristics of opal gemstone structure

processes and consumables needed for cutting and polishing opals

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

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

Assessment must confirm knowledge of the processes for cutting and polishing opals in a range of shapes and the skills to achieve a high quality finish that satisfies the requirements of the jewellery industry

Context of and specific resources for assessment

This unit may be assessed in a work environment or in a simulated work environment or in a combination of these situations

Method of assessment

For valid and reliable assessment of this unit evidence should be gathered through a range of methods to indicate consistent performance

Assessment of this unit of competence will usually include observation of processes and procedures oral andor written questioning on underpinning knowledge and skills and other methods as required

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

Competence in this unit must be assessed over a period of time in order to ensure consistency of performance over the range of variables and contexts applicable to the work environment

Assessment of this competency requires access to

an opal cutting workshop

a qualified workplace assessor or assessment team

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 wax or adhesives for dopping.

Equipment may involve:	appropriate ventilation grinding machinery personal protective equipment polishing machinery sanding machinery saws.

Jewellers' cutting angle requirements may include:	10º to 12º side angle (from setting edge to start of dome) 35º to 45º back setting edge (standard solid) all sharp edges or acute angles be slightly rounded (optional) flat or domed back high overall polish and free of defects proportions of low, medium and high domes be maintained sanded or polished back setting edge to be straight and parallel to back thickness of stone not to exceed 2/3 of width (standard solid) tolerance for standard millimetre sizes, 0.2mil. + or - when leaving potch or boulder on back of stone, maintain proportions in relation to stone size, i.e. approx. 2/3 of width.

Dop may include:	hot or cold dopping Note: cold dopping is preferred as hot dopping may damage the opal and cold dopping is preferable for long term stability.

Shape and dome may include:	a variety of other shapes cabochon dome - high, medium, low free form rectangles shapes.

Treatment may include:	Sugar and acid treatment or sugar and heat treatment for Andamooka matrix (other treatments are used but are not acceptable in the industry) Note: if opal is treated or in any way altered other than cutting and polishing, the treatment must be disclosed to prospective buyers.

General OHS principles and Safe Operating Procedures may include:	complying with the safe operating procedures for each machine or process good housekeeping using personal protection equipment where required.