How fun that you chose to collect seeds ...
, but even if the seeds do turn out to be viable, whatever rose they produce will not be Joseph's Coat.
I hope that doesn't disappoint you.
The only roses that grow true from seed are species roses. All of the other roses, like JC, are hybrid roses, so the seeds produced are either self-seedlings or are open pollenated with the father unknown.
A quick test for seed viability is to put them in a glass of water and soak them for about 15 minutes. Those that float to the top, are most likely not viable.
Even if you plant a "viable" seed, it may not germinate. That means whatever genes that got combined in that seed, just didn't come together in a way that works and the seed aborted. You have to plant a LOT of rose seeds to get seedlings. Then you have to toss a lot of those seedlings because they produce weak plants. However, you can come up with a fantastic rose.
It's still fun.