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

On a four-tier lab scale (None / Minor / Moderate / Significant), 'major oil' colloquially covers Moderate and Significant — the emerald's fissures are heavily filled with cedarwood oil or stabilised resin to improve apparent clarity. This is the most common tier of Colombian emerald in circulation and is industry-standard, openly disclosed practice.

Is a major-oil Colombian emerald a worse stone?

Not inherently — it's a different price tier. Without oil, most Colombian rough would be unsellable. Major-oil delivers Colombian colour, origin, and pedigree at a fraction of the no-oil or minor-oil price. The stone is sound; the trade-off is more required maintenance and tighter resale spreads.

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

Plan on professional re-oiling every 5–10 years for occasional-wear pieces; more often (every 2–3 years) for daily-wear engagement rings. The frequency depends on heat exposure, ultrasonic exposure (avoid), and how heavily the stone was originally enhanced. Skyjems' bespoke programme handles re-oiling for inventory pieces and bespoke commissions.

Can I clean a Colombian emerald in an ultrasonic cleaner?

No. Ultrasonic, steam, hot water, and solvents (acetone, alcohol) can all drive existing oil out of the fissures and crack the filler. Clean only with a soft cloth, mild soap, and lukewarm water. Take the piece to a jeweller for professional cleaning rather than risking home equipment.

Why is the price gap between minor-oil and major-oil Colombian emerald so wide?

Because minor-oil and no-oil emeralds reveal more native clarity and require less long-term maintenance, both of which collectors price in. The auction market separates the categories distinctly. At equivalent size, colour, and origin, minor-oil typically trades at 1.5–3× a major-oil stone, and no-oil can trade at 5–10× or more.

What setting is best for a major-oil Colombian emerald?

Protective settings — bezel, partial-bezel, or channel — are recommended for major-oil emeralds, especially in engagement rings or daily-wear pieces. High-prong solitaire settings expose the stone to edge-wise impact and accelerate oil loss. Skyjems' bespoke programme defaults to bezel for this category. Lead time is typically 4–8 weeks. Contact the curator at +1-416-366-3335 or [book a private viewing](https://skyjems.ca/pages/schedule-a-private-viewing).

ENCYCLOPEDIA · DAVID SAAD · 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

Most Colombian emeralds in circulation are graded "moderate" to "significant" — what the market loosely calls "major oil." For buyers entering the Colombian emerald category, this is the largest and most commonly traded tier. Done well, a major-oil Colombian emerald delivers Colombian colour and provenance at a fraction of the no-oil or minor-oil price point. This guide covers what to expect, what to inspect, and how Skyjems lists this tier.

What "major oil" actually means

Major lab grading scales (GIA, SSEF, Gübelin, AGL) use four tiers — None, Minor, Moderate, Significant. "Major oil" colloquially covers the moderate and significant categories: the emerald's surface-reaching fissures are heavily filled with cedarwood oil or, in some cases, hardened resin, to mask larger inclusion patterns and improve apparent clarity.

Why this tier is the market's largest

Colombian emerald deposits naturally produce stones with abundant fissures. Without enhancement, most material would be unsellable. Industry practice for centuries has been cedarwood oil; modern practice still favours natural oils over polymer resins for stability. Major-oil Colombian emerald is not a defective stone — it is the standard offering, openly disclosed, and the foundation of Colombian emerald jewellery worldwide.

What to inspect before buying

Six checkpoints. (1) Lab report calls out the enhancement degree (Moderate or Significant) — never accept a vendor's claim alone. (2) Origin determination on the report — Colombian, not Zambian or Brazilian. (3) Eye-clean appearance at the table under daylight. (4) Colour saturation — bluish-green is the hallmark; greyish or yellowish casts pull value down. (5) Cut quality — a windowed cut sacrifices light return and is harder to mask with oil over time. (6) Re-oiling disclosure — has the stone been re-oiled, and how recently.

Care for major-oil emeralds

Routine maintenance is more important at this tier. Never expose the stone to ultrasonic cleaning, steam, hot water, or solvents — all can drive existing oil out and crack the filler. Clean only with soft cloth, mild soap, and lukewarm water. Plan on professional re-oiling every 5–10 years, more often for daily-wear pieces.

Setting recommendations

For major-oil Colombian emeralds, protective settings are essential. Bezel, partial-bezel, and channel settings shield the stone from edge-wise impact better than high-prong mounts. Skyjems' bespoke programme defaults to bezel for engagement and daily-wear pieces in this category.

Skyjems inventory snapshot

Browse Colombian emerald inventory at /collections/emerald. The collection covers minor through significant oil grades; lab disclosure is on every product page. Skyjems lists below what retailers carrying our inventory charge, with full traceability from rough to finished piece where available.

Private viewings and bespoke

For Colombian emerald you can compare across oil grades under daylight, contact Skyjems at +1-416-366-3335 or request a private viewing.