القماش ده لونه غامق.

In Egyptian Arabic, the normal spoken pattern is:

noun + demonstrative

So:

• القماش ده = this fabric / this cloth

This is one of the first word-order differences English speakers notice.
If you put ده first, it usually changes the meaning. For example:

• ده القماش = This is the fabric

So in your sentence, القماش ده is exactly the natural Egyptian way to say this fabric.

Because in Egyptian Arabic, this/that normally goes with a definite noun.

So the pattern is not:

• fabric this

but rather:

• the-fabric this

That whole combination means this fabric.

So:

• القماش = the fabric
• القماش ده = this fabric

Even though it looks a little redundant from an English point of view, it is completely normal in Arabic.

لونه is made of:

• لون = color
• ـه = his / its

So لونه literally means its color.

In this sentence, the its refers back to القماش ده.

So the structure is:

• القماش ده = this fabric
• لونه غامق = its color is dark

A very literal breakdown would be:

• This fabric, its color is dark.

That sounds odd in English, but it is very natural in Arabic.

Because in Arabic, present-tense sentences like this often have no written or spoken verb for is/are.

So:

• لونه غامق literally = its color dark
• natural English = its color is dark

This is called a nominal sentence.
In the present tense, Arabic usually just puts the parts next to each other.

If you wanted past tense, then you would use a verb, for example:

• كان لونه غامق = its color was dark

Yes. القماش ده غامق is natural and means This fabric is dark.

The version with لونه is a little more like:

• This fabric is dark-colored
• This fabric, its color is dark

So both are possible, but they are slightly different in feel:

• القماش ده غامق = directly describes the fabric as dark
• القماش ده لونه غامق = focuses specifically on the fabric’s color

Egyptian Arabic often likes this topic + resumptive pronoun pattern, so القماش ده لونه غامق sounds very normal.

Because in لونه غامق, the adjective غامق describes لون (color), and لون is masculine.

So:

• لون = masculine
• therefore غامق = masculine singular

If the adjective were describing a feminine noun directly, you would usually use the feminine form غامقة.

For example:

• الشنطة دي غامقة = This bag is dark

In your sentence, though, the adjective is tied to لون, not directly to some feminine noun, so غامق is correct.

They are related, but not the same form.

In everyday Egyptian Arabic:

• ده = this for masculine singular
• دي = this for feminine singular

In Standard Arabic / MSA, you would use:

• هذا = masculine this
• هذه = feminine this

So ده is the normal spoken Egyptian form.
A native speaker in daily conversation would say القماش ده, not هذا القماش.

A rough Egyptian pronunciation is:

il-ʔamāsh da lōno ghāmeʔ

A few helpful notes:

• القماش: the ق is often pronounced as a glottal stop ʔ in Egyptian Arabic, so it sounds like il-ʔamāsh
• ده sounds like da
• لونه sounds roughly like LOH-no
• غ is a throaty sound, a bit like the French or German r
• غامق in Egyptian is often pronounced ghāmeʔ, with the final ق also becoming a glottal stop

So the whole sentence flows roughly as:

il-ʔamāsh da lōno ghāmeʔ

That is a good way to notice it.

The sentence works as:

• القماش ده = the topic: this fabric
• لونه غامق = the comment about it: its color is dark

So the full structure is basically:

• As for this fabric, its color is dark

Arabic often introduces a noun as the topic, then refers back to it with a pronoun inside the rest of the sentence. English does this much less often, so it can feel unusual at first.

A very natural Egyptian way is:

• القماش ده مش غامق = This fabric isn’t dark

If you want to keep the same structure as your original sentence, you can say:

• القماش ده لونه مش غامق = This fabric’s color isn’t dark

In Egyptian Arabic, مش is the usual way to negate this kind of present-time description.