I've been reading up a lot on Giants/Super Giants, now I'm no expert or a breeder yet but I too have been wanting some.
What I have read says you cannot tell for sure until the Geckos are almost year old(or less if they hit the weight mark). Males have to hit 90grams and Females have to hit 60grams. Now of course I've read that getting babies from Giant x Super Giant crossings should produce all Giants or Super Giants so buying from a reputable breeder would also help. The website below had some facts about Giants/Super Giants.
It is co-dominant, and a couple of us here in Colorado have giants and super giants. Feel free to PM me if you'd like, or email me through my website.
It is hard to tell the difference when young, and even full grown. Weight has NOTHING to do with it. Obviously, a longer, bigger gecko is going to be able to accomodate more weight, and by one year of age should be distinguishable visually, if only just by a little bit of length. As said above, look for someone that is working with true giants, and not placing all of their stock in a scale.
I'm sure thats true but it was a general guideline to go by from what I've read. I mean unless your very experienced with giants and know what body type to look for it would be hard to tell, or if not from someone reputable could be an overfed adult or egg-full female.
I want to see a FULL detailed pairing this season with a Super Giant x Normal (as normal and gene free as possible) and see every hatchling and their development for a minimum of 6 months of development. If everything turns out to be a true "Giant" then I will believe they are incomplete dominant. I know from my experience with working with Giants that I personally didn't feel they were incomplete dominant. I may be wrong and will have no problem admitting it, but I have never seen conclusive proof to prove me wrong. Theories and non documented "facts" don't do it for me.
Chris, the animals I sent you are true giants, make no mistake. At least the two giants are... If you pay close attention, and compare and contrast your animals all the way through maturity, you'll see a difference, albeit sometimes very subtle. Once you have a real super giant, it becomes moot, as there is absolutely no comparison to any non-giants.
i dont doubt that the least bit keith, i know you got it together and i have plenty of faith in your beautiful animals. im already thinking about the next ones i will get from you. my comments were meant for all who are doubting this gene and how it works. i myself have a particular interest and passion for these giants, and intend to dig up any and all info/research i possibly can to better understand every aspect of it genetically, as i have big breeding plans for the future. Keith, i can only say, i just cant wait to get some more geckos from you my friend. thanks again and again buddy