Assessor Resource

CUVOPA05B
Complete pre-cutting processes for opal doublets and triplets

Assessment tool

Version 1.0
Issue Date: March 2024


This unit includes the identification of materials suitable for making into doublets and triplets and selection of backing materials and glues for making the doublets or triplets. 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.

This unit covers skills and knowledge to select and prepare opal and backing materials for cutting as doublets or triplets and complete all precutting processes. It includes documenting and recording all aspects of the procurement and cutting process.

No licensing, legislative, regulatory or certification requirements apply to this unit at the time of endorsement.

You may want to include more information here about the target group and the purpose of the assessments (eg formative, summative, recognition)

Prerequisites

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.


Employability Skills

This unit contains employability skills.




Evidence Required

List the assessment methods to be used and the context and resources required for assessment. Copy and paste the relevant sections from the evidence guide below and then re-write these in plain English.

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

To achieve competency in this unit, a person must be able to select appropriate materials for making into a doublet or triplet and complete all pre-forming processes using safe working practices.

Assessment must confirm the ability to select the materials for making into a doublet and to make decisions on how to cut the material and what the final product should be. It involves preparing the opal and the backing material, flattening the stone and backing and cementing the two together. It also involves using the same skills to make a triplet from a very thin opal layer with a transparent triplet top.

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.

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, evaluation of the final product 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).

Assessment of this competency requires access to:

an opal cutting workshop

a qualified workplace assessor or assessment team.


Submission Requirements

List each assessment task's title, type (eg project, observation/demonstration, essay, assingnment, checklist) and due date here

Assessment task 1: [title]      Due date:

(add new lines for each of the assessment tasks)


Assessment Tasks

Copy and paste from the following data to produce each assessment task. Write these in plain English and spell out how, when and where the task is to be carried out, under what conditions, and what resources are needed. Include guidelines about how well the candidate has to perform a task for it to be judged satisfactory.

Required skills:

use of appropriate equipment and consumables

ability to work safely with opal cutting equipment and materials.

Required knowledge:

the materials that are most suitable for making doublets or triplets

the equipment and consumables needed for making doublets and triplets.

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.

Suitable material may include:

multiple bars of colour with potch between

off-cuts from solid production

opal from unsuitable boulder iron stone

opal prone to crack (triplet only)

opalised shell skins

thin bar of colour in potch

thin seam opal

weak colour on a clear base (jelly opal).

Appropriate equipment may include:

diamond grinder

diamond saw

free-hand saw

silicon carbide grinder

slab saw

trim saw.

Backing materials may include:

black jade

black potch (best)

boulder iron stone

clear or transparent potch

dark grey potch

glass (triplet only)

obsidian (black)

vitrolite (triplet only).

Blacking agents may include:

black epoxy additives

black permanent markers

nigrosine.

Adhesives may include:

Loctite UV 358 or 363 (triplet top to opal)

UHU Plus 24hr (opal to backing)

other glues, such as UHU Quickset, MEGAPOXY 69, EPOXY 330, TENAX+ super glue, BOND 527, TITE ON.

Triplet top materials may include

clear quartz

commercial standards size triplet tops

glass, plain or plate

lead crystal glass

synthetic spinel, corundum, topaz.

General OHS principles and Safe Operating Procedures sheet may include:

complying with the safe operating procedures for each machine

good housekeeping

using personal protection equipment where required.

Copy and paste from the following performance criteria to create an observation checklist for each task. When you have finished writing your assessment tool every one of these must have been addressed, preferably several times in a variety of contexts. To ensure this occurs download the assessment matrix for the unit; enter each assessment task as a column header and place check marks against each performance criteria that task addresses.

Observation Checklist

Tasks to be observed according to workplace/college/TAFE policy and procedures, relevant legislation and Codes of Practice Yes No Comments/feedback
Select suitable materials for cutting as a doublet or a triplet based on market requirements and characteristics of the stone. 
Determine best play of colour and mark that side. 
Check for flaws with powerful light source and correct if necessary. 
Flatten opal on marked side (this will be the best play of colour side) until surface is free of potch and impurities and completely down to the colour bar using appropriate equipment. 
Select backing materials and flatten. 
Lap opal and base until flat satin finish is obtained. 
Clean and dry opal and base. 
Blacken flattened surface with appropriate blacking agent. 
Mix adhesive to manufacturers' instructions. 
Ensure stone is cemented with the best colour face down. 
Cement flattened surfaces together eliminating excess adhesiveness and air bubbles. 
Allow adhesive to harden following manufacturers' instructions. 
Grind stone to expose join between opal and backing. 
Grind stone to expose best colour. 
Grind to rough shape. 
When working with a very thin opal layer, manufacture a triplet. 
Lap the colour surface of the opal until a thin layer of opal remains on the backing. 
Clean and dry stone. 
Cement manufactured triplet top or preferred alternative to the opal surface eliminating excess adhesive and air bubbles. 
After curing, grind the stone to expose both joins. 
Follow all general OHS principles and Safe Operating Procedures when using machinery for opal cutting. 

Forms

Assessment Cover Sheet

CUVOPA05B - Complete pre-cutting processes for opal doublets and triplets
Assessment task 1: [title]

Student name:

Student ID:

I declare that the assessment tasks submitted for this unit are my own work.

Student signature:

Result: Competent Not yet competent

Feedback to student

 

 

 

 

 

 

 

 

Assessor name:

Signature:

Date:


Assessment Record Sheet

CUVOPA05B - Complete pre-cutting processes for opal doublets and triplets

Student name:

Student ID:

Assessment task 1: [title] Result: Competent Not yet competent

(add lines for each task)

Feedback to student:

 

 

 

 

 

 

 

 

Overall assessment result: Competent Not yet competent

Assessor name:

Signature:

Date:

Student signature:

Date: