Assessor Resource

CUVOPA404A
Cut opal spheres and beads

Assessment tool

Version 1.0
Issue Date: May 2024


Those applying the skills and knowledge in this unit produce spheres and beads to industry standards in a workshop environment and use and maintain machinery as required.

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 produce opal spheres and beads, including the selection of the rough opal through to the drilling and final polishing.

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:

identify and safely use machinery and equipment to cut and polish opal beads and spheres to meet the requirements of industry.

Context of and specific resources for assessment

Assessment must ensure access to:

machinery, equipment and consumables required to produce opal beads and spheres.

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 finished 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.

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 investigate other methods of making spheres and beads where commercial equipment isn’t available

planning and organising skills to organise required materials

problem-solving skills to deal with contingencies

numeracy skills to use numerical features of machinery

technical skills to:

use appropriate machinery and equipment

select appropriate material for beads and spheres.

Required knowledge

suitability of rough for production of beads and spheres, taking into account the level of wastage and cost

equipment and consumables needed for the process

industry standards for opal beads and spheres

OHS issues related to machinery.

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.

Bead mill, sphere making equipment and drills may include:

Arrowhead Gemcraft (USA) Sphere Machine

E & J Adams Lapidary (USA) Sphere Machine

home-made equipment

Mahashi (Japan) Bead Mill

Richardson’s (USA) Sphere Machine.

Maintenance areas may include:

bead mill:

all bearings

all electrics

bead holders and wear factor

bottom rotating disc and wear factor

rubber pad on top rotating disc

sphere makers:

all electrics

assorted sphere cups

polishing pads

reduction boxes.

Materials suitable for making spheres and beads may include:

any opal material, taking into account a yield factor or recovery rate of only 10% to 15% from a given ounce of rough opal

beads of a variety of regular or free form shapes

spheres cut from any opal material, with consideration of yield factor.

Grinding mediums may include:

diamond powder #80 through to #1200

silicon carbide grit #80 through to #1200.

Polishing mediums may include:

cerium or tin oxide

diamond powder #3000 through to #100,000.

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 bead mill, sphere-making equipment and drills to manufacturers’ specifications 
Identify the maintenance areas and complete the required maintenance routine 
Investigate other methods of making spheres and beads if commercial equipment is not available 
Select materials suitable for making spheres or beads 
Preform opal using saw or grinder to produce required shape 
Grind shape corners to establish rounded form 
Fill holder template with pre-formed beads (range of shapes) 
Grind pre-formed beads in bead mill using #120 silicon carbide powder until they are rounded 
Change the holder template to a small size if necessary 
Remove faulty or broken opal from the bead mill 
Remove beads from the bead mill and clean 
Select beads for drilling 
Place bead in bead vice, drill half way into the bead, turn over, check alignment and drill the other half ensuring a cut hole through the bead 
Place cleaned beads in tumble polisher with increasingly fine grinding medium 
Clean tumbler and beads at every change over 
Clean beads thoroughly after the final grind, place in the tumbler with polishing medium and tumble to a high lustre 
Clean finished beads thoroughly with water 
Select opals to make spheres and pre-form the spheres 
Grind the spheres in a sphere maker with water and increasingly fine grinding medium 
Clean spheres thoroughly at each change over 
Polish cleaned sphere with polishing medium and water using leather sphere cups to desired polish 

Forms

Assessment Cover Sheet

CUVOPA404A - Cut opal spheres and beads
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

CUVOPA404A - Cut opal spheres and beads

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: