What does 'major oil' or 'significant enhancement' mean on a Colombian emerald?

GIA grades emerald clarity enhancement as minor, moderate, or significant. 'Major oil' is a market term often used for moderate or significant enhancement. Clarity enhancement is a common and disclosed practice.

Is a major-oil Colombian emerald a worse stone?

Enhancement extent is one disclosed characteristic, not a complete quality grade. Compare the exact report wording, visible fissures, transparency, colour, cut and price for the individual stone.

How often should a major-oil emerald be re-oiled?

There is no universal schedule. The filler, condition and wear history can differ by stone. If the appearance changes, consult a professional jeweller or gemologist before arranging any treatment.

Can I clean a Colombian emerald in an ultrasonic cleaner?

Avoid steam cleaning and use caution with ultrasonic cleaning because emeralds are commonly fractured and may be clarity enhanced. Use mild soap and lukewarm water; for professional cleaning, take the piece to a jeweller.

What should a lab report tell me about a Colombian emerald?

A lab report from a reputable laboratory can specify the emerald's origin (e.g., Colombia) and the degree of clarity enhancement (minor, moderate, or significant). Always review the report for the specific stone you are considering.

ENCYCLOPEDIA · SKYJEMS

Colombian Emerald — Major Oil Buying Guide

Name: Skyjems
Address: 27 Queen St East, Suite 1011, Toronto, ON, M5C 2M6, CA
Telephone: +1-416-366-3335
Price range: $$$$

Key concepts: colombian emerald, major oil, significant clarity enhancement, emerald cleaning, colombian emerald price

Colombian emeralds are commonly clarity enhanced. "Major oil" is trade wording rather than a GIA grade, and sellers may use it for stones whose reports describe moderate or significant clarity enhancement. Always use the exact wording on the report supplied with the stone.

What "major oil" actually means

GIA describes the extent of emerald clarity enhancement as minor, moderate, or significant. That finding is not an overall clarity grade. Clarity enhancement can involve filling surface-reaching fissures with substances such as oil or resin to improve apparent clarity.

Clarity enhancement in Colombian emeralds

Colombian emeralds are often clarity enhanced, and oiling is a traditional practice. Cedarwood oil is one filler that has been used, but the report for an individual stone may use different wording or identify a different filler.

What to inspect before buying

Checkpoints:

Read the report's exact enhancement conclusion rather than relying on the listing term "major oil."
Check the report's geographic-origin opinion if Colombian origin matters to the purchase.
Inspect the stone face-up and from the side for visible fissures and overall transparency.
Compare hue, tone and saturation between individual stones.
Inspect the cut and face-up appearance rather than judging from carat weight alone.

Care for major-oil emeralds

Avoid steam cleaning and use caution with ultrasonic cleaning. Clean with mild soap and lukewarm water. The appearance of a filled fracture can change over time, but there is no universal re-oiling schedule; have the stone inspected if its appearance changes.

Skyjems inventory snapshot

Browse Colombian emerald inventory at /collections/emerald. Review each listing for its clarity-enhancement disclosure.

Contact Skyjems

For more information, you can reach Skyjems at +1-416-366-3335 or visit their website.

Sources and further reading

Emerald Quality Factors — GIA
Classifying Emerald Clarity Enhancement — GIA
The Oil Treatment of Emeralds in Bogotá, Colombia — GIA
Emerald Care and Cleaning — GIA
GIA Colored Stone Research — GIA