Assessor Resource

CUVOPA403A
Use a faceting machine

Assessment tool

Version 1.0
Issue Date: April 2024


Those applying the skills and knowledge in this unit produce individual pieces that comply with commercial standards in a workshop environment where there is access to faceting machines and consumables appropriate for use in faceting opals.

Where appropriate the outcomes of this unit could be contextualised to apply to other gemstones.

This unit describes the performance outcomes, skills and knowledge required to use a faceting machine to facet opal, including selecting material, pre-forming, and cutting and polishing a selected stone. The machine may be used to produce a traditional faceted gemstone and also to complete a range of other tasks, such as making cubes from opal material.

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

Prerequisites

Not applicable.

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.

Overview of assessment

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

Evidence of the ability to:

select opal pieces suitable for faceting

use faceting equipment to produce and polish a faceted opal that conforms to industry standards

follow all OHS requirements for machinery and equipment procedures.

Context of and specific resources for assessment

Assessment must ensure access to:

a faceting machine

appropriate consumables.

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 and other methods as required

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.

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

critical thinking and analytical skills to select appropriate opal pieces

problem-solving skills to deal with contingencies and OHS issues

numeracy skills to use numerical features of machinery

technical skills to:

facet, grind and polish stones and maintain equipment

set up equipment to manufacturer specifications.

Required knowledge

suitability of opal pieces for faceting

equipment and consumables required for opal faceting process

industry standards for faceting.

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.

Faceting machines may include:

Facetron (USA)

Gemmasta (Aus)

Graves (USA)

jamb peg

Platform

Poly-Metrics (USA)

Post

Raytech (USA)

Ultra Tec (USA).

Machine components may include:

angle vernier (protractor)

coarse and fine height adjuster

coolant tank

forward and reverse switch

handpiece (quill)

index wheel

master lap

radial vernier (cheater)

sliding post

variable speed control.

Laps’ diamond grit size may include:

coarse #80, #100, #120, #180

fine #800, #1000, #1200

medium #220, #320, #360, #400, #600

polish #14000, #50000, #10000

pre-polish #2400, #3000, #8000.

Maintenance checklist may include:

check electrics regularly for faults and water seepage

cover machine when not in use

keep all laps separate from each other

keep whole machine clean

oil and clean moving parts

read manufacturer manual and keep near machine.

Opal suitable for faceting may include:

Australian clear jelly opal

Australian electric blue opal

contra-luz

Mexican cherry opal

Mexican fire opal

any transparent opal.

Angles may include:

critical angle 43½º

crown main 43º

culet angle 44º

girdle breaks, main angle plus 6º to 15º

pavilion main 45º

star facets, main angle minus 15º

table facet 0º.

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
Set up faceting machines to manufacturers’ specifications identifying machine components and laps 
Complete manufacturers’ maintenance checklist 
Investigate index wheels for quill and identify main and critical angles for opal 
Select piece of opal suitable for faceting 
Pre-shape using faceting machine or bench grinder to establish crown and pavilion 
Dop stone and work on pavilion first 
Place dopped stone in quill and align to create girdle 
Grind girdle to desired shape on medium to fine lap 
Grind main facets at main angle on medium to fine lap 
Grind girdle break facets at girdle break angle on fine lap 
Grind culet facets at culet angle on fine or pre-polish lap 
Fine lap, pre-polish and polish all pavilion facets including girdle 
Transfer stone to suitable dop 
Remove crown dop and place new dop and stone in faceting quill 
Place girdle facet on lap at 90º, index setting 64 or 96 and lock quill 
Grind girdle break facets at break angle establishing girdle thickness, on a medium to fine lap 
Grind main facets at main angle on fine lap 
Cut table facet on fine lap, to 40% of total width of stone 
Pre-polish all crown facets 
Grind star facets using pre-polish lap 
Polish all facets 
Remove stone from dop and clean 

Forms

Assessment Cover Sheet

CUVOPA403A - Use a faceting machine
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

CUVOPA403A - Use a faceting machine

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: