This lesson is not meant to teach you to distrust sellers. Most essential-oil sellers in Vietnam are honest and believe what they say.
The problem is that the trade circulates a number of phrases that sound like facts but are actually empty, and they are passed from supplier to retailer to customer without anyone stopping to check.
"One hundred per cent pure"
No authority issues this certification. It is a self-made claim.
Ask back: Show me the analysis of this lot — and what lot number will be printed on the bottle?
"Therapeutic grade"
This phrase sounds like a technical classification. No independent organisation defines or awards it.
Ask back: Who awards that grade, and where can it be looked up?
"Imported directly from France"
Where it is bottled is not where the plant grew. A great many essential oils are grown and distilled in India, Bulgaria or Indonesia and then bottled in Europe.
That in itself is not bad. But the advertising line is letting you misunderstand the origin.
Ask back: Where was the plant grown, and where was it distilled?
"It smells exactly the same in every lot"
This is the only phrase on the list where consistency is a bad sign.
Natural raw materials vary with the season, with altitude, with the time of harvest. A product that stays absolutely stable over many years has either been blended to be uniform, or is not what it claims to be.
Ask back: Show me the analyses of three different lots.
"It is certified organic, so it is certainly pure"
Organic certification is about how the crop is grown: no synthetic pesticides, no chemical fertilisers. It says nothing about whether the bottle has been blended at a later stage.
Two different issues, two different systems of checking.
Ask back: Is the organic certificate issued for the growing area or for this lot? And do you have a separate analysis for the lot?
"Suitable for all ages"
This is the only phrase on the list that touches on safety, and also the one to be most careful with.
Many essential oils carry specific recommendations for young children and pregnant women, and those recommendations differ with the oil and the concentration. A blanket claim for every age and every oil is not careful enough.
Ask back: What are the specific recommendations for this oil, and what source are they based on?
How to use this list
Put these six questions to every supplier you intend to buy from.
And pay attention to how they answer, not only to what they answer. That is a fact about the seller, and it is often more reliable than anything printed on the label.