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Evidence Guide: CUVOPA201A - Identify and assess opal

Student: __________________________________________________

Signature: _________________________________________________

Tips for gathering evidence to demonstrate your skills

The important thing to remember when gathering evidence is that the more evidence the better - that is, the more evidence you gather to demonstrate your skills, the more confident an assessor can be that you have learned the skills not just at one point in time, but are continuing to apply and develop those skills (as opposed to just learning for the test!). Furthermore, one piece of evidence that you collect will not usualy demonstrate all the required criteria for a unit of competency, whereas multiple overlapping pieces of evidence will usually do the trick!

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CUVOPA201A - Identify and assess opal

What evidence can you provide to prove your understanding of each of the following citeria?

Develop knowledge of opal geology

  1. Identify the geological conditions suitable for the formation of opal and apply the theories of opal formation
  2. Determine sources of opal worldwide and locations of opal fields
Identify the geological conditions suitable for the formation of opal and apply the theories of opal formation

Completed
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Determine sources of opal worldwide and locations of opal fields

Completed
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Apply the principles of grading and quality assessment to opal

  1. Identify the principles used for valuing opals in terms of base and background colours, predominant colours and patterns, and other factors that influence an opal’s value
  2. Apply principles of valuing to determine the potential value of opals
Identify the principles used for valuing opals in terms of base and background colours, predominant colours and patterns, and other factors that influence an opal’s value

Completed
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Apply principles of valuing to determine the potential value of opals

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Distinguish natural opal from man-made varieties

  1. Determine the gemmological characteristics of opal based on knowledge of varieties of opal found worldwide
  2. Select gemmological instruments to authenticate natural opal
  3. Use the selected instruments to authenticate opal
  4. Identify substances used to simulate opal and synthetic opal-like substances and compare their characteristics to natural opal
Determine the gemmological characteristics of opal based on knowledge of varieties of opal found worldwide

Completed
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Select gemmological instruments to authenticate natural opal

Completed
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Use the selected instruments to authenticate opal

Completed
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Identify substances used to simulate opal and synthetic opal-like substances and compare their characteristics to natural opal

Completed
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Identify and describe the different types of opal

  1. Identify opals of various types and describe them using correct terminology
  2. Develop a general awareness of types of opal treatments and determine which are acceptable in the industry
Identify opals of various types and describe them using correct terminology

Completed
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Develop a general awareness of types of opal treatments and determine which are acceptable in the industry

Completed
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Assessed

Teacher: ___________________________________ Date: _________

Signature: ________________________________________________

Comments:

 

 

 

 

 

 

 

 

Instructions to Assessors

Evidence Guide

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:

identify and describe the characteristics of the different types of opal using correct terminology and equipment

apply principles of valuation and determine the authenticity of opal materials.

Context of and specific resources for assessment

Assessment must ensure access to:

opals from various sources.

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 and/or written questioning on underpinning knowledge and skills

evaluation of the final product

review of portfolios of evidence

review of third-party workplace reports of on-the-job performance by candidate.

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).

Guidance information for assessment

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

Required Skills and Knowledge

Required skills

communication skills to describe and document opal identification information

literacy skills to interpret information about opals

planning and organising skills to organise basic work practices

numeracy skills to apply valuation principles

technical skills to use gemmological instruments

technology skills to find information on opals.

Required knowledge

sources of information on the opal industry

valuation systems for opal

functions of various opal industry sectors, including mining dealing and manufacturing jewellery

accepted terminology for describing opal

safety issues associated with the use of gemmological instruments.

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.

Formation of opal may include:

opal combining with other minerals

opal formed in:

sedimentary deposit

volcanic deposit (igneous)

erratic boulders

replacement cavities (nobbies, glauberite)

seams

volcanic and erosion sediments

opal replacing:

fossils

wood.

Sources of opal worldwide may include:

Australia

Brazil

Hawaii

Indonesia

Mexico

Slovakia

USA.

Locations of opal fields may include:

New South Wales – Lightning Ridge and White Cliffs

Queensland – various places including Winton, Quilpie, Jundah and Yowah

South Australia – Coober Pedy, Mintabie and Andamooka.

Base and background colours may include:

black

boulder – ironstone

dark

light.

Predominant colours and patterns may include:

colours, such as:

blue

green

orange

red

violet

yellow

patterns, such as:

broad

Chinese writing

flagstone

harlequin

peacock tail

pin fire

rolling flash

sheen

straw.

Other factors that influence an opal’s value may include:

availability of supply

economic climate

mining restrictions

origin

political situation

rarity

weight

whether the sale is wholesale or retail.

Principles of valuing may include:

body colour

brilliance

inclusion and imperfections

pattern

play of colour

predominant colour

quality of cut (shape/proportions)

shape, size and weight

thickness of colour bar

type.

Gemmological characteristics may include:

chemical composition

colour

fracture

hardness

phosphorescence

refractive index

specific gravity.

Gemmological instruments may include:

microscope

refractometer

S.G. scales

standard 10X loupe

ultraviolet lamps.

Natural opal is classified as:

common opal and potch

precious opal.

Substances used to simulate opal and synthetic opal-like substances may include:

simulants – Gilson opal

synthetics – for example plastics and slocum stone.

Opals of various types may include:

composite natural opal – doublets, triplets, mosaic and chip opals

natural opal type 1 – opal in one piece in its natural state apart from cutting and polishing

natural opal type 2 – opal naturally attached to the host rock – boulder opal

natural opal type 3 – opal intimately diffused as infilling in pores or between the grains of the host rock – matrix opal

varieties of opal:
(N1 to N9 represents gradation from black to white in approximately 10% intervals)

black – opal which shows a play of colour within or on a black or very dark body tone (N1, N2, N3, N4)

dark – opal which shows a play of colour within or on a dark body tone (N5, N6)

light – opal which shows a play of colour within or on a light body tone (N7, N8, N9).

Opal treatments:

may include treatments applied to improve appearance, structure or durability

any treatment other than cutting and polishing must be disclosed.