Cutting holes within shapes

[c0de]

Hello.
I'm trying to make a cube with a hole on one face. I'm using blending to add transparency when drawing the cube. Is it possible to draw a polygon (hole) on one face of the cube and keep the cube blending options? I would like to see through that hole the inside edges/corners of the cube.

I tried to use Stencil and this is the result I got:

As you can see, other objects are visible through the stencil surface but the inside corners of the same object not.
This is the code I used to generate the objects:

GLuint GLWidget::makeObject(GLuint listid, GLfloat x, GLfloat y, GLfloat z)
{
    GLuint list = glGenLists(listid);
    glNewList(list, GL_COMPILE);
  //  glPushMatrix();
   glClear(GL_STENCIL_BUFFER_BIT);
    glEnable(GL_STENCIL_TEST);
    glClearStencil(0);
    glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, Pearl[AMBIENT]);
    glMaterialfv(GL_FRONT_AND_BACK, GL_SHININESS, Pearl[SHININESS]);
    glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, Pearl[DIFFUSE]);
    glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, Pearl[SPECULAR]);
    // glColorMask(0,0,0,0);
     glStencilFunc(GL_ALWAYS, 1, 1);
     glStencilOp(GL_KEEP,GL_KEEP,GL_REPLACE);
//	glDepthMask(GL_FALSE);
    glBegin(GL_QUADS);
    	  glNormal3f(  0,  y,  0 );
    	  glVertex3f(  x/2,  y, -z/2 );
	  glNormal3f(  0,  y,  0 );
  	  glVertex3f( -x/2,  y, -z/2 );
	  glNormal3f(  0,  y,  0 );
	  glVertex3f( -x/2,  y,  z/2 );
	  glNormal3f(  0,  y,  0 );
	  glVertex3f(  x/2,  y,  z/2 );
    glEnd();
  //  glColorMask(1,1,1,1);
   // glDepthMask(GL_TRUE);
    glStencilFunc(GL_NOTEQUAL, 1, 1);
    glStencilOp(GL_KEEP,GL_KEEP,GL_KEEP);
 
    glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, Ruby[AMBIENT]);
    glMaterialfv(GL_FRONT_AND_BACK, GL_SHININESS, Ruby[SHININESS]);
    glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, Ruby[DIFFUSE]);
    glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, Ruby[SPECULAR]);
    glBegin(GL_QUADS);
    //top
    	  glNormal3f(  0,  y,  0 );
    	  glVertex3f(  x,  y, -z );
	  glNormal3f(  0,  y,  0 );
  	  glVertex3f( -x,  y, -z );
	  glNormal3f(  0,  y,  0 );
	  glVertex3f( -x,  y,  z );
	  glNormal3f(  0,  y,  0 );
	  glVertex3f(  x,  y,  z );
    glEnd();
     glStencilFunc(GL_ALWAYS, 1, 1);
     glStencilOp(GL_KEEP,GL_KEEP,GL_KEEP);
    glBegin(GL_QUADS);
    //bottom
	  glNormal3f(  0, -y,  0 );
	  glVertex3f(  x, -y,  z );
	  glNormal3f(  0, -y,  0 );
  	  glVertex3f( -x, -y,  z );
	  glNormal3f(  0, -y,  0 );
	  glVertex3f( -x, -y, -z );
	  glNormal3f(  0, -y,  0 );
	  glVertex3f(  x, -y, -z );
 
    //front
    	  glNormal3f(  0,  0,  z );
	  glVertex3f(  x,  y,  z );
    	  glNormal3f(  0,  0,  z );
	  glVertex3f( -x,  y,  z );
    	  glNormal3f(  0,  0,  z );
	  glVertex3f( -x, -y,  z );
    	  glNormal3f(  0,  0,  z );
	  glVertex3f(  x, -y,  z );
    //back
    	  glNormal3f(  0,  0, -z );
	  glVertex3f(  x, -y, -z );
	  glNormal3f(  0,  0, -z );  
	  glVertex3f( -x, -y, -z );
	  glNormal3f(  0,  0, -z );  
	  glVertex3f( -x,  y, -z );
	  glNormal3f(  0,  0, -z );  
	  glVertex3f(  x,  y, -z );
    //left
	  glNormal3f( -x,  0,  0 );  
	  glVertex3f( -x,  y,  z );
	  glNormal3f( -x,  0,  0 );
	  glVertex3f( -x,  y, -z );
	  glNormal3f( -x,  0,  0 );
	  glVertex3f( -x, -y, -z );
	  glNormal3f( -x,  0,  0 );
	  glVertex3f( -x, -y,  z );
    //right
 	  glNormal3f(  x,  0,  0 );
	  glVertex3f(  x,  y, -z );
	  glNormal3f(  x,  0,  0 );  
	  glVertex3f(  x,  y,  z );
 	  glNormal3f(  x,  0,  0 );
	  glVertex3f(  x, -y,  z );
	  glNormal3f(  x,  0,  0 );  
	  glVertex3f(  x, -y, -z );
 
    glEnd();
    glDisable(GL_STENCIL_TEST);
 
//    glPopMatrix();
    glEndList();
    return list;
}

The materials are defined as follows:

#define AMBIENT 	0
#define DIFFUSE 	1
#define SPECULAR 	2
#define SHININESS 	3
static float Pearl[][4] = {
	{0.250000, 0.207250, 0.207250, 0.22000}, //0.922000
	{1.000000, 0.829000, 0.829000, 0.22000},
	{0.296648, 0.296648, 0.296648, 0.22000},
	{11.264000}
};
 
static float Ruby[][4] = {
	{0.174500, 0.011750, 0.011750, 0.550000},
	{0.614240, 0.041360, 0.041360, 0.550000},
	{0.727811, 0.626959, 0.626959, 0.550000},
	{76.800003}
};

Am I setting up the stencils wrong? I dont think I understands very well how does they work...

Any help would be appreciated.
Thanks

[c0de]

Fixed. It was all about lighting... added a light inside the cube and the edges are visible now.