The oldestCedar oil“oil”
- What it is
- A natural colorless oil.
- Over time
- Not permanent Can seep out with heat; the stone can be re-oiled.
- Removal
- Possible by a professional.
- For you
- The most traditional. Gentle care is enough.
Reading your stone's product page
Emerald treatments cedar oil, liquid resin, hardened resin
Almost every emerald receives a product in its fissures to make them less visible. Two pieces of information matter on a product page: the product used and the degree of clarity enhancement.
01The three treatments
Oil, liquid resin, hardened resin: what sets them apart
All three products fill the fissures that reach the surface. They do not behave the same way over time.
| Compare | The oldestCedar oil“oil” | Common in ColombiaLiquid resin“Palma oil” | The most durableHardened resinwith hardener |
|---|---|---|---|
| What it is | A natural colorless oil. | A synthetic resin, without hardener. Despite its name, it is not a plant oil. | A resin that sets in the fissure once a hardener is added. |
| Over time |
Not permanent Can seep out with heat; the stone can be re-oiled. |
More stable than oil Its durability depends on the product used. |
Designed to stay Stable over time. |
| Removal | Possible by a professional. | Possible by a professional. | More difficult. |
| For you | The most traditional. Gentle care is enough. | Not to be confused with hardened resin. Same precautions as oil. | Generally worth less on the market: the treatment is permanent, and it is most often applied to stones with larger fractures. |
Common in ColombiaLiquid resin“Palma oil”
- What it is
- A synthetic resin, without hardener. Despite its name, it is not a plant oil.
- Over time
- More stable than oil Its durability depends on the product used.
- Removal
- Possible by a professional.
- For you
- Not to be confused with hardened resin. Same precautions as oil.
The most durableHardened resinwith hardener
- What it is
- A resin that sets in the fissure once a hardener is added.
- Over time
- Designed to stay Stable over time.
- Removal
- More difficult.
- For you
- Generally worth less on the market: the treatment is permanent, and it is most often applied to stones with larger fractures.
02Before and after
What filling changes
- aBefore: the air in the fissures reflects light, so they look white and dry.
- bDuring: the product, with an index close to emerald's, takes the place of the air.
- cAfter: the fissures show less and apparent clarity improves. The stone itself stays the same.
03The degree
From “No oil” to “significant”: the amount of product
The degree measures the extent of clarity enhancement. It is neither a percentage of oil nor a quality grade for the stone.
-
No oilNo filling
The laboratory detects no product.
-
InsignificantInsignificant
Traces, with almost no effect on appearance.
-
MinorMinor · F1
A limited improvement. The most common degree in our selection.
-
ModerateModerate · F2
A more noticeable improvement; the filling plays a larger part.
-
SignificantSignificant · F3
The stone's appearance depends mostly on the filling.
How to read the wording on a certificate
A mention often combines two pieces of information. The degree is always given; the product, not always.
Excerpt from a laboratory report
Clarity enhancement : Minor (oil)
The degreeThe product
Wording varies from one laboratory to another. Your stone's report conclusion is what counts.
04Our oiling
An example of the oiling process for a stone at Johya
We oil some stones ourselves with cedar oil, in a machine, under vacuum, with heat and pressure. Here, a 3.11 ct baguette, minor oil degree.
01The stone before oiling
Already cut, no filling. 
02The oil used
A cedar oil. 
03In the machine
Vacuum, heat and pressure draw the oil in. - Video04
The stone after oiling
CD56 after oiling, in motion.
Framing and lighting change from one photo to the next: they do not measure the degree, which is a matter for gemological examination.
05Under the microscope
Inclusions and fissures: what gets filled, what does not
A natural emerald almost always contains inclusions: its jardin. These are crystals, cavities filled with liquid and gas, and fissures that healed during growth.
Treatment only reaches fissures open to the surface. Inclusions enclosed in the stone stay as they are, and they are often what lets a laboratory recognize a natural stone.
Read our article on the jardin
06Care
Good habits
- No ultrasound, no steamThey can dislodge the product from the fissures.
- No solventsAnd no strong heat. A soft cloth and lukewarm water are enough.
- Tell the jewelerBefore a setting or a repair, give them the stone's treatment.
07Questions
Before you choose
Is the degree enough to judge an emerald's quality?
No. It tells you about the clarity enhancement, not about the stone's beauty. Color, transparency, cut and weight still need to be looked at. A minor degree does not mean “no inclusions”.
How can you tell which product was used?
The laboratory examines the stone and may rely on spectroscopy. Not every report names the product. If the information is missing, ask us to clarify it for the stone in question.
Is a resin worth less than oil?
The name of the product does not set the price. Degree, color, transparency and weight count too. To compare two stones, read their reports in full, not just the “oil” or “resin” label.
Can a stone be re-oiled?
Yes, if the filling has deteriorated. This work is entrusted to a professional after examining the stone. Do not try to remove the product yourself.
What the law says
French decree no. 2002-65 exempts impregnation with a colorless fluid substance, a traditional practice, from the word “traité” (treated), but not from informing the consumer. The solidified fillings of article 2 require the word “traité” and an information sheet supplied with the invoice.
On our product pages, we state the treatment and its degree. The details are in our authenticity and treatment disclosure policy.
