Leto, I'm sure you got the wrong idea of what 'Week - 15' and 'Week - 16' stands for. Following your Sim's calendar (underneath your time you'll see how many weeks you have been playing Sims), your nectar will have Week - XX when you make it. So from what you have said, your Life Fruit Flame Fruit Nectar was made on Week 15 and a week before the other bottle.
But you're welcome to share the recipe for that nectar. Maybe it really is a breakthrough recipe you have.
Sure I will, but I doubt you don't know this one already: it is 60% lifefruit, 30% flamefruit and 10% cherimola grapes. But that recipe is already known on this site. I like this one because it provides your sim with all the mootlets in one cup that gives you a total moodlet count of, I believe, 110 or so.
Mostly I make just three different types of nectar: the one above that my Sims drink on vacation lots and sometimes at home when I want the elders to stay around the living Sims for a few days more. I keep the Life Fruit Pomegranate for the increase of value and I also have some Flamefruit Cherry nectar for when my Sims needs to get happy without getting younger.
Now that I think of it: I believe that a 60% lifefruit, 30% flamefruit and 10% cherry will be even more valuable than my above described recipe because I thought that cherries are more worth than cherimola grapes. But I haven't tested it yet.
Thanks for the week explanation, by the way. That makes a lot more sense to me now. Of course, the older the bottle, the more valuable it gets, but compared to the really huge bottle, I've just compared the wrong two.
[Edited quote section. -Pam]