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Given an integer $n in Bbb{Z}$, we understand $root 3 of n$ to mean the number $x in Bbb{R}$ such that $x^3 - n = 0$. Then $Bbb{Q}(root 3 of n) subset Bbb{R}$, right? The same then goes for the ring of algebraic integers $mathcal{O}_{Bbb{Q}(root 3 of n)}$.

Since $root 3 of {-n} = -root 3 of n$, it follows that $Bbb{Q}(root 3 of n) = Bbb{Q}(root 3 of {-n})$ and likewise $mathcal{O}_{Bbb{Q}(root 3 of n)} = mathcal{O}_{Bbb{Q}(root 3 of {-n})}$. So in order for a ring adjoining a cubic root to $Bbb{Q}$ to have complex numbers we need a cubic root that is imaginary or complex.

Therefore, given $$omega = frac{-1 + sqrt{-3}}{2}$$ and $n > 1$, the ring of integers of $Bbb{Q}(omega root 3 of n)$ should contain complex numbers. What about the ring of $Bbb{Q}(i root 3 of n)$? That is a distinct kind of rings than the other two I've mentioned, right?

Is this all correct? What kinds of cubic rings have I overlooked?

Things are so easy at algebraic degree $1$, we only have $textbf Z$ to worry about.

At algebraic degree $2$, we have infinitely many real quadratic integer rings and infinitely many imaginary quadratic integer rings, but it still feels manageable because we're only dealing with two kinds of rings, plus $textbf Z$.

Construct a polynomial of the form $x^2 + bx pm 1$, where $b in textbf Z$. The "$pm 1$" bit helps us narrow our focus down to units. By the quadratic equation, if we choose to go with $-1$, we have $$x = frac{-b pm sqrt{b^2 + 4}}{2}$$ (in some cases you might have to rewrite things like $sqrt{200}$ so that you have a squarefree number under the radical symbol).

When we go to algebraic degree $3$, the complexity suddenly explodes. And we find that complexity by doing for cubics something similar to what we did for quadratics just now. Construct a polynomial of the form $x^3 + ax^2 + bx pm 1$, where $a in textbf Z$ also. For example, $1 - root 3 of 2$ is a zero of $x^3 - 3x^2 + 3x + 1$.

But try to solve $x^3 + x^2 - x + 1$, that turns out to be way beyond my meager computational skills. I turn to Wolfram Alpha for help, and it gives three answers all involving $root 3 of {19 - 3 sqrt{33}}$. Whoa.

So yeah, you have overlooked a lot of kinds of rings.

It is a bit unclear to me exactly what kind of an answer you are looking for. Listing the following points that occurred to me while reading the question.

1. You don't need to use $omega$ to get a cubic extension field containing non-real numbers. Any cubic polynomial $f(x)$, irreducible over $Bbb{Q}$, such that $f$ has only a single real zero will yield such fields. For example, $f(x)=x^3-2x+2$, irreducible by Eisenstein, has a single zero $in(-2,-1)$. If $alpha$ is one of the complex zeros of $f$, then $K_1=Bbb{Q}(alpha)$ is a cubic field, and $Bbb{Z}[alpha]$ is a ring that as a an abelian group is free of rank three. The field $K_1$ cannot be gotten by adjoining a cube root (real or complex) of an integer to $Bbb{Q}$. A way of seeing that is to use the discriminants. The discriminant of $f(x)$ is $d(f)=-76$, implying that the discriminant of $mathcal{O}_{K_1}$ is either $-76$ or $-19$. The discriminant of $g(x)=x^3-n$ is $d(g)=-27n^2$. The discriminants of orders of the same field can only differ by a factor that is a square, making it impossible for $mathcal{O}_{K_1}$ to contain $Bbb{Z}[omega^jroot3of n]$ for any alternative $j=0,1,2$ (so any root of $g(x)$).


2. Some cubic extension fields of $Bbb{Q}$ are Galois extensions, implying that the minimal polynomials of all the elements have real zeros (all in that same field). An example appearing possibly the most frequently in our website is $K=Bbb{Q}(2cos(2pi/9))$. The zeros of the irreducible polynomial $p(x)=x^3-3x+1$ are $2cos(2^kpi/9)$ with $k=1,2,3$, cyclicalle permuted by the mapping $rmapsto r^2-2$. The ring of integers of $K$ is $Bbb{Z}[2cos(2pi/9)]$. Here the discriminant is $d(p)=81$, the square of a rational number. This happens always with cubic Galois extensions.


3. The third primitive root of unity $omega$ does play the following important role, so I will also mention the following result (look up Kummer theory for details and generalizations). If, instead of $Bbb{Q}$, we use $F=Bbb{Q}(omega)$ as our base field, then we have the following characterization of cubic Galois extensions of $F$.
   
   

   
   

   Assume that $L$ is a cubic Galois extension of $F$, then there exists an element $zin L$ such that $alpha=z^3in F$. In other words $L=F(root3ofalpha)$.

   
   

   
   

Of course, in the last bullet, $F$ has other types of cubic extensions, but none of those are Galois over $F$.