Emerald Filler Clarity: New Price Guides for Clarity-Enhanced Emeralds Now in the GemGuide
New charts distinguish between cedarwood oil and resin-treated Colombian emeralds
Gemworld International, publisher of the GemGuide, best known for its gem pricing guide charts for all significant gem materials, has introduced important updates to its emerald pricing charts in the May–June 2025 issue. For the first time, pricing for Colombian emeralds is separated by enhancement type, with distinct charts for stones treated with cedarwood oil and those treated with resins.
[For greater detail on oil and resin enhancements, see Brecken Branstrator’s feature in the GemGuide magazine, “Emerald Fillers and Today’s Market: Demand and Pricing.”]
According to Stuart Robertson, President of Gemworld International, the change was prompted by feedback from the retail sector.
“We had some requests to include more specifics about enhancement types in our emerald section,” Robertson explained. “These requests were from larger corporate retail firms, not miners or wholesalers.”
A Shift in Market Expectations
The revised charts show that most of the obvious price changes occur in the fine and extra-fine qualities, particularly where per-carat prices increase incrementally with each carat jump — especially after 1 carat. This trend was confirmed during Gemworld’s market research at the Tucson shows, prompting a revamp in both price structuring and treatment categories.
“We expanded the number of weight categories in the emerald charts by narrowing the weight range of each grid,” he said. “We also researched prices for finer grades treated with cedarwood oil in response to a manufacturing retailer.”
The updated page (page 50 of the May–June issue) features two separate charts:
▻ The top chart covers Colombian emeralds treated with cedarwood oil.
▻ The bottom chart covers those treated with resin-based fillers.
Pricing Resin vs. Oil: Why It Matters
In the high-end Colombian emerald market, cedarwood oil continues to be the preferred filler — and that preference is now reflected in the GemGuide‘s pricing structure.
“When it comes to Colombian emeralds, especially the higher quality stones, buyers want cedarwood oil,” Robertson said. “There is a price difference — slight at times — between cedarwood oil and resin-filled but otherwise comparably looking stones.”
[Again, we refer you to Branstrator’s feature, “Emerald Fillers and Today’s Market: Demand and Pricing,” which explains the differences between oil and resin fillers.]
“We spoke with Fernando Garzon at Clarity Enhancement Laboratory in New York and got great information,” Robertson said. “Some of the stones we examined had lab reports, but those reports don’t — and often can’t — state the exact filler.”
Addressing Ambiguity in Treatment Disclosure
Gemworld is taking a realistic approach to treatment classification — one that mirrors how The GemGuide handles geographic origin in its pricing methodology.
“We are approaching these charts the same way we approach origin,” Robertson noted. “It is based on trusted representations with the understanding that the actual result could be different.”
To acknowledge the variability and proprietary nature of some resins, the GemGuide will include a clarifying note in future issues:
“Prices reflect general guidelines for common oil and resin fillers. Stones treated using proprietary resin-type enhancements [like ExCel] will require a premium.”
Industry Feedback Expected
These changes are not set in stone. Robertson emphasized that the GemGuide would continue refining the emerald charts as new feedback comes in.
“We are expecting feedback to continue to come in as the charts circulate,” he said. “We will refine the charts as appropriate as market conditions change.”
Similar updates are also underway for ruby and blue sapphire pricing, where Gemworld’s research has found a comparable link between size and per-carat price escalation.
The Bottom Line
This update reflects a move toward more detailed and realistic pricing — especially in high-end colored stones, where clarity enhancements can make a big difference in value.
For those dealing in fine Colombian emeralds, the GemGuide’s latest charts offer a clearer framework for pricing — while reinforcing the importance of accurate disclosure and up-to-date documentation at the point of sale.
