Advice for your Aunt Mark  

Dear Aunt Mark,
I am no expert but I know that dings in tempered glass windshields can be repaired with some kind of resin stuff.  Below are google images of this.  It looks like the device they use would not work well on the edge of the glass but maybe there is some other way to apply it and shape it, I dunno.  (If you scroll down far enough, there is a photo of a sign that says chips are $20 to fix.)
https://www.google.com/search?q=repaired+chip+in+windshield&rlz=1C5CHFA_...
PS, Gorilla Glue foams up and the bubbles in it will make the repair more visible---I wonder if Super Glue would be less hellish looking?  Probably not a lot less, though.

I think If the top were tempered, the unfortunate encounter would likely have resulted in a large pile of very small pieces. I suspect it's not, in which case the edge can be re-ground and polished.  Maybe Knoll can confirm this.
Hxtal epoxy is specially formulated to have a refractive index similar to glass and is sometimes used for repairs.

Tktoo is correct. Hxtal is the go to adhesive for gluing and laminating glass. It is very expensive and you need a fine (gram or finer) scale to mix the two parts. It is also very watery at first which makes it not great as a filler. It also has a very long set up time, at least 24 hours. You would have to build a perfect dam around the wound to hold the adhesive and chip till it sets. A lamp with a 100 watt incandescant bulb placed near the repair site will speed up the set time.
Next down the list is a UV glue for glass. You will need a UV light to activate (set) the adhesive.
Third, and my pic for you would be a gem setting epoxy. I use epoxy 330. It is easy to find online. It behaves more like a normal 2 part epoxy and does not require such precise measurement or a UV light. It is also less runny at the start. It will set in 20-40 mins. or thereabouts. You will still need a barrier around the wound to stop it from flowing out. 
For any of these you will have to get rid of all of the adhesive you have already used first.
I hope this helps.

You are all so sweet to respond, many thanks.
I hadn't even thought about a repair kit, but probably because the bruise is as deep as the beveled edge, it wouldn't look perfect enought for picky old me, so I will probably just ride my bicycle over to the local DWR this weekend and order a replacement.  I did have a stiff bloody mary just after the collision, and was trying to imagine what I should do with being faced in such a sad situation, and was temporarily thinking of a wood or travertine top to replace the glass..but somehow the table wouldn't be the same (hidden legs, etc).  I've been looking at other lovely tables (on line) all morning, and for the $$$, I can't find another that I would like as well.  I'll sniff aroud the b&b italia tables.
With fond,
Aunt Mark

If you are prone to clunking into the table as it sits, it might be a good time to select something softer and less chippable for this spot, and you can put the ol' Barcelona in the basement (or whatever).
 
'cause when the new one breaks to pieces that'll really be a bummer!
(cue Gang of Four's "Damaged Goods")

I second tktoo in having a hard time believing this is tempered glass if you can take a chunk out of it this size. I've never been able to chip a piece of tempered glass without complete disintegration. (Don't ask).
There is a simple test for tempered glass looking at it through polarized sunglasses, you can see the internal stress in the glass. Perhaps you have a pair, Mark?
And if it isn't tempered, perhaps you can get it ground....

I would think so, too.  Tempered glass can't be modified; I'd be pretty sure this isn't tempered.  
Car windshields are laminated, rather than tempered;  the side windows in the car are tempered. You've seen the crumbled class on the sidewalk -- that's from car windows that have been shattered by vandals and thieves. Windshields crack, but it's the outer layer that cracks, separated by the plastic layer from the inner ply of glass.  This is designed to prevent ejection of passengers in a crash.
A glass supplier said I shouldn't order a 1/2" glass top to be tempered, because it would be destroyed if hit too hard. A chip is a less catastrophic damage -- and a thick glass top very seldom cracks through, he said.  Looks like Knoll agrees with that . . .

Dear Design Poodles,
I can't thank you all enough for all of your input.  So..here is my plan of attack.
This afternoon the person (people?) who installed my recent impact resistant exterior windows/doors are stopping by to do a simple repair.  I will ask them to verify whether or not me or my glass top have a temper.   This glass company does not  have a saw capable of munching through 3/4 inch glass.
Then on Monday morning I have a person that manufactures/installs glass shower doors coming to measure the bathrooms.  This glass company does have a big-bad saw that would do the job.  Maybe they can point me in the right direction.
What has been interesting to me is that it is 20% cheaper to order an entire Barcelona table (thru DWR on sale), than it is to replace the glass top.  I will keep you all posted!
I've also considered calling one of those car windshield repair facilities to see if that might hide the wound.
 
Best to all,
Aunt Mark
 
ps I have not yet called Knoll ( I know...sorry niceguy).  also there are no indications in the corners (stamp) signifying tempered glass..

Mark,
With your multiple homes, cars, vacations, designer shoe collection etc you can surely afford to replace it.  Why would you get a half ass patch job done?  Put this on craigslist or the like and put the money collected towards another.

I certainly can't blame you for rushing to repair the damage -- just as we clap our hand over a cut and "wish it better" without delay.  However, some repairs need to be done right the first time; now that glue has been introduced, it could be too late to use the superior substances prescribed here.  Just a heads-up . . .
Glass can be cut, but it's risky and difficult to take just a little off -- the thicker, the worse, I'm afraid. Once cutting is done, the glass houses have an automatic grinder-polisher that the glass is passed through, on edge.  The places I've dealt with all seem dedicated to using that device as little as possible -- they won't guarantee a perfect size when you order, citing a +- factor of 1 1/16" for anything over window glass thickness, and more for the thicker materials.  They cut, that leaves waves in the edge, and the grinder-polisher takes those waves out.  It seems to me they could hit the size "right on" if they cut a bit large and ground down until the number was reached -- but no . . .
Not your problem here, of course.  They could potentially put your damaged edge through the grinder as many times as it takes to get rid of the chip; I doubt that they would agree to do that. It may be that they have to change the abrasive wheels or polishing ones often, and want to avoid excessive wear on those -- I don't know . . .

Thanks jdip.
Problem solved, no further advice sought.
Best,
Mark

if memory serves me right, I believe that the barcelona comes with Knoll's starfire glass which is not tempered.  Knoll offers tempered glass and will generally say if the glass is tempered.  

The Starfire glass might be more colorless than ordinary plate ?

End of story haiku.
 
Yes, non-tempered, chop 
Starfire not this chunk,no
$100.
 
 
 
hi,
 
Your Aunt M.