Ratio of Total Weight (RTW)
Ratio of Total Weight (RTW)
A chain-of-custody accounting model used by RJC-certified refiners and manufacturers
Ratio of Total Weight (RTW) is one of three chain-of-custody accounting models recognised under the Responsible Jewellery Council (RJC) Chain-of-Custody (CoC) standard, alongside Segregation and Mass Balance. RTW provides a methodology by which entities that handle mixed certified and non-certified materials — typically refiners and manufacturers operating commingled production lines — can make proportional CoC claims on output products in line with the proportion of certified input material they have processed over a defined accounting period.
The three RJC CoC models
The RJC Chain-of-Custody standard, first published in 2012 and revised periodically since, provides three pathways for entities to make CoC claims on jewellery materials. Segregation requires that certified material be physically separated from non-certified material at every stage from production through final sale; the model offers maximum traceability but is operationally restrictive. Mass Balance permits the mixing of certified and non-certified material in shared production but requires that the volume of CoC-certified output not exceed the volume of CoC-certified input; the model permits commingling while preserving an integer-volume audit trail.
Ratio of Total Weight is the third model. Under RTW, an entity tracks the percentage of certified input material in its overall throughput over a defined accounting period and may make percentage CoC claims on its output products to that proportion. RTW is structurally similar to Mass Balance but expresses the claim as a percentage of total throughput rather than as an integer volume of certified product.
How RTW works in practice
Consider a refiner that receives 60 per cent of its gold input from CoC-certified sources and 40 per cent from non-certified sources during a quarterly accounting period. Under Segregation, the certified gold would be processed in physically separated pour batches and sold as fully CoC-certified product, with the non-certified gold processed and sold separately. Under Mass Balance, the refiner could pour mixed product but could only sell up to 60 per cent of total quarterly output as CoC-certified. Under RTW, the refiner could mark every output product as 60 per cent CoC-certified material by weight.
The RTW approach matches commercial reality at refiners and manufacturers where physical separation is impractical and where the integer-volume Mass Balance model would underrepresent the certified content of any individual product. The trade-off is reduced traceability: an RTW-claimed product cannot be linked to a specific certified input batch in the way that a Segregated product can.
When RTW is used
RTW is most relevant in refining and primary fabrication, where multiple input streams are processed through shared equipment that cannot be cleaned between batches at reasonable cost. Refining of gold and platinum-group metals is the principal context. The model is less relevant downstream in the supply chain, where individual jewellery pieces are typically traceable to specific manufacturing batches and Mass Balance or Segregation accounting is more appropriate.
Some entities operate hybrid arrangements, applying Segregation to high-value or premium-claim products and RTW or Mass Balance to general production. The choice of accounting model is the entity's, subject to the RJC's auditing of the chosen approach.
Auditing and assurance
RTW claims are subject to the same independent auditing as Segregation and Mass Balance claims under the RJC framework. Auditors verify that the entity's input certifications are valid, that the throughput tracking is accurate over the accounting period, and that the percentage claim made on output products corresponds to the verified input proportion. Discrepancies trigger non-conformance findings under the RJC standard and may, in serious cases, lead to suspension of the entity's CoC certification.
The auditing process is similar in structure to that of the broader RJC Code of Practices for ethical jewellery sourcing, but with specific attention to the volume and percentage tracking that distinguishes RTW from the other CoC models.
Position relative to other standards
Other standards exist for chain-of-custody accounting in precious-metals supply chains. The London Bullion Market Association (LBMA) Responsible Gold Guidance, the OECD Due Diligence Guidance for Responsible Supply Chains of Minerals from Conflict-Affected and High-Risk Areas, the Fairmined gold standard, and the Fairtrade gold standard each provide their own frameworks. The RJC's CoC standard, including its RTW provision, is the most widely adopted accounting framework for jewellery industry purposes.
In the trade
For dealers and brand operators, the practical relevance of RTW is in understanding what a CoC certification actually covers. A claim of "100 per cent CoC-certified gold" implies Segregation; a claim of "60 per cent CoC-certified gold by weight" implies RTW; a Mass Balance claim is typically expressed as a volume figure. Buyers should be familiar with the three models and read CoC documentation accordingly. The model used affects what the certification means about the specific piece in hand, even when all three approaches are recognised by the RJC framework.