JC Keepsake Brendan Jewelers Despite Lifetime Warranty, ring broken, diamond lost, company out of business! Westminster, Colorado

My husband bought me a nice diamond ring from JC Keepsake, with 10 diamonds channel-set. A few years later, he bought me one with 3 larger diamonds in a pressure setting, "floating" above the band. Both times he bought the lifetime warranty, with the stipulation that I get the rings cleaned and checked every 6 months.
I lost a diamond from the 3 diamond ring, but found it, and brought it in & had it re-mounted. I was assured that "that never happens". Sadly, it did happen again, with me losing it somewhere, about a year ago, and JC is long since out of business, not honoring its agreement nor having any recourse for us to have the diamond replaced.
I now have a ring with 2 diamonds and a big gaping hole where the third one was. Each of the diamonds were 13 carat, and as such, I suppose were worth around $500 each...I am sad and angry about the whole thing.
What kind of company goes out of business and leaves no recourse for their customers? Ripoff!