This unit requires the application of research skills to determine market preferences for buying of cut and polished opal so that decisions can be made on how to cut the opal to gain the best yield and show of colour. It also covers the ability to carry out all the precutting planning, cleaning and preforming of the gemstone while working safely with materials and equipment. Advanced processes needed for pre-cutting black and boulder opals is covered by CUVOPA13B Apply advanced pre-cutting processes to complex opals

Where appropriate the outcomes of this unit could be contextualised to apply to other gemstones. Examples of aspects of the unit that may need to be adjusted would include:

the specific properties of each gemstones

industry and market requirements

underpinning knowledge

Range Statement.

This unit may be assessed on its own or it may be assessed with other units that cover related skills and knowledge.

Evidence is most relevant when provided through an integrated activity which combines the Elements of competency for the unit, or a cluster of units of competency.

ELEMENT

PERFORMANCE CRITERIA

1 Survey market requirements as a basis for making a decision on opal cutting strategy.

1.1 Establish the current client opal buying preferences (cut and polished) in the retail, and wholesale markets.

1.2 Determine the Internet buying preferences for cut and polished opal.

1.3 Document client buying preferences for cut and polished opal.

2 Weigh opal and record information.

2.1 Weigh opal before cleaning as a basis for determining yield.

2.2 Record relevant information.

3 Clean and orient opal to determine yields and shape.

3.1 Make an assessment of the stone and consult with supervisor, colleagues, client or other appropriate persons.

3.2 Rub down (clean) to expose the colour face using appropriate equipment.

3.3 Determine best orientation for gemstone.

3.4 Establish the top and bottom of the stone.

3.5 Remove unwanted material.

3.6 Check for internal flaws with powerful light source.

3.7 Determine where to cut the stone (or stones) to maximise value taking yield and colour play into consideration and cut stone.

4 Process opal to pre-form state.

4.1 Remove unwanted material from the planned gemstones using appropriate equipment.

4.2 Grind to the desired shape.

4.3 Check for internal flaws and correct if necessary.

5 Follow OHS principles when operating machinery.

5.1 Follow all general OHS principles and Safe Operating Procedures when using machinery, tools, materials and equipment for opal cutting.

Required skills:

research skills

use of appropriate equipment

planning skills

ability to determine colour and yield to achieve greatest value.

Required knowledge:

characteristics of opal gemstone structure

the importance of achieving yield when cutting a gemstone

market trends and industry requirements.

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 current buying trends, retail, wholesale and Internet. Based on this information and knowledge of opal structure and value, decisions are made on what the final product should be and how to cut the stone to achieve the desired outcome maximizing the yield and colour play from each stone. Assessment must confirm the safe completion of cleaning and shaping and preforming.

Context of and specific resources for assessment

This unit may be assessed in a work environment, 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 and/or written questioning on underpinning knowledge and skills and other methods as required.

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

Assessment methods should closely reflect workplace demands (e.g. literacy) and the needs of particular groups (e.g. 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:

a computer

an opal cutting workshop

a qualified workplace assessor or assessment team.

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.

Determining opal buying preferences may involve:

accessing Internet auction sites

accessing Internet opal specific sites

making contact with opal dealers

making contact with opal-cutters

phoning jewellery wholesalers

phoning other jewellers

talking with local jewellery store owner

targeting opal specific stores.

Relevant information to be recorded may include:

date of purchase

description

description of area where mined

field

mining lease number

number of classes

purchase price

type of opal

vendor

weight.

Appropriate equipment may include:

cleaning equipment

diamond grinder

diamond sawing

free-hand saw

silicon carbide grinder

slab saw

trim saw.

Unwanted material may include:

cracked material

iron stone

materials with inclusions or stains

matrix

poor colour

potch

sandstone.

General OHS principles and Safe Operating Procedures sheet may include:

complying with the safe operating procedures for each machine

good housekeeping, in particular avoiding contaminants

using personal protective equipment where required.

Opal cutting and polishing

This unit contains employability skills.