Application
This unit requires the application of knowledge and skills in a range of environments from cutting and polishing to retailing, wholesaling, selling on the internet or mining.
Prerequisites
Not applicable.
Elements and Performance Criteria
1. Develop knowledge of opal geology | 1.1 Identify the geological conditions suitable for the formation of opal and apply the theories of opal formation 1.2 Determine sources of opal worldwide and locations of opal fields |
2. Apply the principles of grading and quality assessment to opal | 2.1 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 2.2 Apply principles of valuing to determine the potential value of opals |
3. Distinguish natural opal from man-made varieties | 3.1 Determine the gemmological characteristics of opal based on knowledge of varieties of opal found worldwide 3.2 Select gemmological instruments to authenticate natural opal 3.3 Use the selected instruments to authenticate opal 3.4 Identify substances used to simulate opal and synthetic opal-like substances and compare their characteristics to natural opal |
4. Identify and describe the different types of opal | 4.1 Identify opals of various types and describe them using correct terminology 4.2 Develop a general awareness of types of opal treatments and determine which are acceptable in the industry |
Required Skills
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.
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: 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. |
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: 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. |
Sectors
Opal cutting and polishing
Employability Skills
This unit contains employability skills.
Licensing Information
No licensing, legislative, regulatory or certification requirements apply to this unit at the time of endorsement.