As you suggested, I moved it to the forum.

Ok, I am wondering about the diminished 2nds, 3rds, etc. You said they weren't used much.
Can you please explain when we are supposed to use these grades?

Also, the augmented chords, I know where I could apply these, but I would like to hear your opinion about their flavor and when to use.

Thanks muris!

First of all,diminished second would sound just like root
so you can have that only if composer is trying to mess with our brains.
Per example,in key of A you get note Bbb,that would be dim 2nd.
As for 3rd you have similar idea,dim 3rd would be just like 2nd
so once again it's not that often in use except if composer
really wants to write it that way.

Augmented is usually related to 5th actually.
Aug chord contains root,major 3rd and sharp(aug) 3rd.
This chord is used a lot in Jazz on 5th degree,like a dominant chord.
In key of D or Dm per example,you have A aug chord on 5th degree,
notes are A,C# and E#.
Now,this E# might confuse you cause it's the same thing as F note,right?

Here's the deal.
All of these chords have ordinary structure based on root,3rd,5th etc.
Now,starting from A, 5th has to start with letter E,
so you can have Eb,E ,E# etc,depends of type of 5th.
And if you say F then you have another aug chord but not A,it's F aug chord this time!!
It's in inversion cause its original shape is F,A and C#.

Now you are realizing one other thing,similar like dim7 chord.
Aug chord is actually made of 2 major 3rds intervals,
if you continue higher you'll get root note once more.
In dim 7 chord you have structure of 3 minor 3rds and next
note higher is root again.

Hope this helps somehow.

Thanks, very logical!

Another question about scale phrasing.

The reason we say E.G E# is becuase we only allow One of each note in a scaleline, right?

Would love to help here but I'm not sure what E.G E# is?

E.G means for example

Edit:

Etymology

Abbreviation of Latin exempli gratiā (“‘for example’”)

Oh yeah,that's is rule for diatonic worlds,when we have 7 notes in scale
and each letter (C,D,E,F,G,A and can be used just once.

But in this aug chord we actually break those rule.
Per example,in key of Dm we have note F as a 3rd.
Now,for A aug we have to use E# for sharp/aug 5th
and this is where to move into chromatic world.
But as I said,aug chord is big flavor in Jazz
and we all know that Jazz is much more than pure diatonic.

Cool man, thanks.
I actually downloaded a huge DVD session with John mclaughlin.
Even he couldn't explain how the chromaticism works, it made him laugh

It is hard to explain all that in few sentences indeed,
there are many things going on there and you
have to try/play it by yourself before you fully understand it.

Yeah, huge topic. I think I'll stick to modes and improv.
Need a better ear for such.

After modes you'll get to chromatics,it's natural way of things.
Have fun playing and ask if you need anything else.

Thanks again man

Anytime.