Stanza 6 Summary

Get out the microscope, because we’re going through this poem line-by-line.

Counting the red stars and those of plum-color.
The sun rises under the pillar of your tongue.

The speaker now tells us that she spends all night counting "red stars" and also ones that are "plum color[ed]." Hmm, red and purple stars—what's up with that?
Well, next the speaker describes the sun rising from under the "tongue" of the statue.
This makes us wonder if the red and purple stars are somehow a reference to taste buds.
You know, if you stick your tongue out and look at it, the taste buds do kind of look like red and purple stars. Come on, you know you want to try it.
We also notice that the speaker is bringing back some of that Roman Forum imagery by describing the tongue as a "pillar," which is pretty much the same thing as the columns she was alluding to before.
So again, the speaker seems to be somehow inside the body of this mega-gigantic statue.

My hours are married to shadow.

Even though the sun is rising, the speaker is still focused on darkness. In fact, she's "married" to it.
Could this be a reference to the way she feels forever bound by the depression caused by the death of her father?
Notice that she chooses to say that her "hours" are married. To us, this gets across the awful feeling of time slowly, agonizingly inching by. That's not really a fun marriage to be in.

No longer do I listen for the scrape of a keel
On the blank stones of the landing.

The speaker chooses to end with a little boat imagery—no, not imagery of a little boat, but a little imagery about boats.
This is a little weird, because there hasn't been any of that stuff up until now, but whatevs. Of course, the original Colossus was by the harbor of Rhodes, so it does make sense.
A keel is that ridge that runs along the bottom of some kinds of boats. The idea of one scraping a landing—where boats, you know, land— seems to imply that a boat has returned home to shore.
The stones are blank, though, without any decoration or importance. Could the speaker be saying that she's ceased to wait for her father to come home?
If this is true, then it makes it even sadder that she's unable to leave these ruins. She knows he'll never come, but still she waits.
She began the poem by telling him that she'll never be able to put him back together, but every day of her life that's what she spends her time trying to do.
The speaker is trapped in the ruins of what he was.