Pigmentul este albastru.

Because -ul is the definite article attached to the end of the noun in Romanian.

So:

• pigment = a pigment / pigment
• pigmentul = the pigment

Unlike English, Romanian usually puts the definite article at the end of the noun instead of before it.

Este means is. It is the 3rd person singular form of the verb a fi = to be.

So:

• eu sunt = I am
• tu ești = you are
• el/ea este = he/she/it is

In this sentence, Pigmentul este albastru, este links the subject with the description, just like is in English.

Yes. E is a very common short form of este in everyday Romanian.

So both are correct:

• Pigmentul este albastru.
• Pigmentul e albastru.

The full form este can sound a little more careful or formal, while e is very common in normal speech.

Because Romanian usually follows the same basic pattern here as English:

subject + to be + adjective

So:

• Pigmentul = the pigment
• este = is
• albastru = blue

That makes Pigmentul este albastru a very normal word order.

Because albastru is an adjective here, not a noun, and it is being used as a predicate adjective after este.

In English, this is like the difference between:

• the blue pigment
• the pigment is blue

In Romanian:

• pigmentul albastru = the blue pigment
• pigmentul este albastru = the pigment is blue

After este, the adjective normally does not take the definite article.

Yes. Romanian adjectives agree with the noun in gender and number.

Here, pigment is a neuter noun, and in the singular, neuter nouns use the same adjective form as masculine singular nouns. That is why you get:

• pigmentul este albastru

If it were plural, neuter nouns behave like feminine, so you would say:

• pigmentele sunt albastre = the pigments are blue

So the form albastru is correct because the noun is singular.

It is generally treated as a neuter noun in Romanian.

That means:

• in the singular, it behaves like a masculine noun
• in the plural, it behaves like a feminine noun

So you get patterns like:

• un pigment albastru = a blue pigment
• două pigmente albastre = two blue pigments

This masculine-in-the-singular / feminine-in-the-plural behavior is typical of Romanian neuter nouns.

A rough pronunciation guide is:

peegh-MEN-tool YES-teh al-BAS-troo

A few notes:

• g in pigmentul is a hard g, like in go
• e in este is pronounced clearly, not silent
• ă does not appear in this sentence, so there is no special central vowel here
• tru in albastru is pronounced, not reduced away

A more IPA-like version would be approximately:

/piɡˈmentul ˈjeste alˈbastru/

Not normally, because pigmentul is specifically definite: the pigment.

If you wanted a more general or indefinite meaning, you would use:

• Un pigment este albastru = A pigment is blue
• Pigmentul este albastru = The pigment is blue

So the -ul ending is important for showing that a specific pigment is being talked about.

Yes, but that would change the structure.

If the adjective goes before or after the noun inside the noun phrase, you get something like:

• pigment albastru = blue pigment
• pigmentul albastru = the blue pigment

But in your sentence, albastru is not inside the noun phrase. It comes after este and describes the subject:

• Pigmentul este albastru = the pigment is blue

So both patterns exist, but they do different jobs.