Είναι από τη μία ακριβή, από την άλλη αυθεντική.

Because Greek often leaves the subject unstated when it is clear from context. This is very normal.

So Είναι ... can mean:

• It is ...
• She is ...
• This is ...

depending on what was mentioned before.

In this sentence, the adjectives ακριβή and αυθεντική are feminine singular, so the omitted subject is understood to be a feminine singular noun.

Greek adjectives must agree with the noun they describe in gender, number, and case.

Here they are used after είναι, so they are predicative adjectives:

• ακριβή = feminine singular
• αυθεντική = feminine singular

That tells you the thing being described is feminine singular.

For comparison:

• masculine: ακριβός, αυθεντικός
• feminine: ακριβή, αυθεντική
• neuter: ακριβό, αυθεντικό

So if the hidden subject were a feminine noun like τσάντα, ιδέα, or έκδοση, these forms fit.

It is a very common Greek contrast structure meaning:

• on the one hand ... on the other hand
• or more literally, from one side ... from the other side

It introduces two different, often contrasting points about the same thing.

So the sentence is presenting two sides of the same object or idea:

• one side: ακριβή
• other side: αυθεντική

The preposition από is part of this fixed expression. In this sentence, it is not really about physical movement.

This is because of the final -ν in the feminine article την.

In Modern Greek, that final -ν is often:

• kept before a vowel
• often dropped before many consonants

So here:

• τη μία: μία starts with μ, so dropping the -ν is normal
• την άλλη: άλλη starts with a vowel, so the -ν is kept

That is why the sentence has:

• από τη μία
• από την άλλη

This is standard and natural.

Yes. Both μία and μια exist.

Very roughly:

• μια is more common in everyday writing
• μία can feel a bit more careful, formal, or emphatic

In this expression, many people write:

• από τη μια, από την άλλη

and many also write:

• από τη μία, από την άλλη

Both are natural. The version in your sentence is perfectly correct.

Yes, you can think of an understood noun such as:

• πλευρά = side
• μεριά = side

So the full idea is something like:

• από τη μία πλευρά
• από την άλλη πλευρά

But Greek very often omits πλευρά or μεριά because the shorter expression is so common.

That is why από τη μία ... από την άλλη works on its own.

Because these adjectives are predicates, not attributes.

Compare:

• η ακριβή τσάντα = the expensive bag
  Here the adjective comes before the noun and has an article relationship with it.

• η τσάντα είναι ακριβή = the bag is expensive
  Here the adjective comes after είναι, so it is predicative and normally has no article.

Your sentence uses the second pattern:

• Είναι ... ακριβή ... αυθεντική

So no article is needed before those adjectives.

Yes, ακριβός / ακριβή / ακριβό can mean either:

• expensive
• accurate / exact / precise

Context decides which meaning is intended.

In this sentence, because it is paired with αυθεντική and because of the meaning you were given, ακριβή is understood as expensive, not precise.

The comma separates the two parallel parts of the contrast:

• από τη μία ακριβή
• από την άλλη αυθεντική

It helps the reader hear the pause and structure clearly.

In careful writing, the comma is very natural here. It shows that the sentence has two balanced halves.

Yes. Greek has several similar contrast expressions. For example:

• Από τη μια είναι ακριβή, από την άλλη αυθεντική.
• Είναι ακριβή από τη μία, αυθεντική από την άλλη.
• Από τη μία πλευρά είναι ακριβή, από την άλλη αυθεντική.
• Από τη μια μεριά ακριβή, από την άλλη αυθεντική.

These all keep the same basic idea.

Your original sentence is natural and concise, especially if the context already makes the subject clear.

Greek word order is more flexible than English word order.

Starting with Είναι is completely natural, especially when the subject is already understood from context. It gives a compact, slightly elegant structure:

• Είναι από τη μία ακριβή, από την άλλη αυθεντική.

But other orders are possible too, such as:

• Από τη μία είναι ακριβή, από την άλλη αυθεντική.

The meaning stays basically the same, though the emphasis may shift slightly.