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Tiếng Việt

Learn · Part Four — Learning to doubt · Lesson 1 of 9

One hundred per cent pure is a claim, not a certificate

No authority issues anything called a purity certificate. The phrase on the label is worth exactly the reputation of whoever printed it.

Walk past any essential-oil stall and you will see the phrase on almost every bottle: one hundred per cent pure.

Stop for a second and ask: who confirms that?

Nobody

In Vietnam, as in most of the world, there is no authority that issues purity certificates for essential oils. No seal, no code number, no list you can look up.

There are international technical standards describing the acceptable composition ranges for each essential oil — the ISO standards are an example. But they are reference documents for buyer and seller to agree on, not certificates issued for a bottle of goods.

There are organic labels such as USDA Organic or EU Organic, but they certify how the crop was grown, not that the bottle you hold has not been blended.

So what is the phrase one hundred per cent pure on the label? It is a sentence the seller wrote themselves.

Three phrases with no legal meaning

One hundred per cent pure. Self-declared, checked by nobody.

Therapeutic grade. This phrase sounds like a technical classification. It is not. No independent organisation defines or awards it. It was born in marketing and stayed there.

Food grade. This phrase has a meaning in some legal frameworks for additives, but it concerns the level of impurities allowed in food processing, and says nothing about whether an essential oil has been blended.

What can replace it

A composition analysis of the very lot you are holding, stating the lot number, date of analysis, laboratory name, instrument and chromatography column.

This is not a certificate. It is data, and data can be checked. You can compare the component proportions with the known range for the species, compare between lots, and spot the unusual signs the next lesson describes.

What matters is the very lot. An analysis covering a whole product line, with no lot number, is almost worthless: it may be the analysis of one good lot, copied and reused for every lot afterwards, including poor ones.

The question to ask

Not is this product pure — that question only invites the seller to repeat the advertising.

But: show me the analysis of this lot, and tell me the lot number printed on the bottle.

The answer to the second question tells you more than every line on the label.

Further reading for this part

A shared list for the whole of Part Four — Learning to doubt, not a note for every sentence. We state what each source was used for.

  1. European Union. Regulation (EC) 1223/2009 and its amendment (EU) 2023/1545 The basis for the list of allergens that must be declared on labels. The 2023 version extends it from 24 to about 80 substances, and the compliance date for new products is 31 July 2026.
  2. Ministry of Health of Vietnam. Circular 06/2011/TT-BYT on the management of cosmetics The legal framework that applies in Vietnam, together with the ASEAN Cosmetic Directive. We do not claim that ASEAN has or has not adopted the EU’s 2023 extension.
  3. International Fragrance Association. The IFRA Standards Concentration limits for individual components in finished products. Unlike ISO, which deals with the composition of raw materials, IFRA deals with safe levels of use.

One thing must be said plainly. We have not read every work above in the original; most of the knowledge comes through secondary literature and reviews. We say so rather than let the list suggest a depth of research we have not reached.

Last updated: September 2026