Assessor Resource

CUVOPA10B
Cut opal spheres and beads

Assessment tool

Version 1.0
Issue Date: April 2024


This unit requires the application of knowledge and skills to the production of the spheres and beads to industry standards. It involves the use and maintenance of machinery and is applied in a workshop environment.

Where appropriate the outcomes of this unit could be contextualised to apply to other gemstones. Examples of aspects of the unit that may need to be adjusted would include:

the specific properties of each gemstones

industry and market requirements

underpinning knowledge

Range Statement.

This unit covers the skills and knowledge to produce opal spheres and beads including the selection of the rough opal through to the drilling and final polishing.

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 produce opal beads and spheres to industry standards.

The assessment must confirm that the person is able to identify and safely use machinery and equipment to cut and polish opal beads and spheres to meet the requirements of industry.

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 finished 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:

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

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:

skills in using and maintaining the machinery and equipment

skills in selecting appropriate material for beads and spheres.

Required knowledge:

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

knowledge of the equipment and consumables needed for the process

industry standards for opal beads and spheres.

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, wear factor

bottom rotating disc, wear factor

rubber pad on top rotating disc

sphere makers:

all electrics

assorted sphere cups, wear factor

polishing pads

reduction boxes.

Materials suitable for making beads or spheres may include:

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

beads may be a variety of regular or free form shapes

spheres can also be cut from any opal material, again the yield factor must be considered.

Grinding mediums may include:

diamond powder #80 through to #1200

silicon carbide grit #80 through too #1200.

Polishing mediums may include:

cerium or tin oxide

diamond powder #3000 through too #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 bead and spheres if commercial equipment is not available. 
Select materialssuitable for making beads. 
Pre-form 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 preformed beads in bead mill using #120 silicon carbide powder until they are rounded. 
Change the holder template to a small size if necessary. 
Faulty or broken opal is removed 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 grindingmedium. 
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

CUVOPA10B - 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

CUVOPA10B - 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: