Any idea how to get past level 15?

I'm on level 15, where you have to make the four large red stones and many many smaller ones of all colors. I've tried many different ways to get the four large stones and still be able to get all the smaller ones, but I always run out of stones. Any suggestions?

I do know that I can get one large red one right away by adding a few more red stones to the big block of red the game gives you to start, and that I can get two more at once by building up my power-ups to use the hourglass, but I still end up losing the level.

I am stuck on level 11, I think it is. I can't get the two large stones for the crown. I, too, have tried a lot of different things, but just can't get that large purple stone before I run out of jewels even using the power ups. Now with what you wrote, I kind of wonder why I am an in such a hurry to move up levels.....lol. Your current level sounds much harder than the one I am on. But I really like how this game makes you think. Happy gaming!

This is what worked for me on level 15:

Fill in all tiny yellows (3-in-a-row), then continue doing yellow 3-in-a-row to build up to hourglass bonus. Turn all the jewels in the top two rows to red except for 6 in other colors in between to prevent any matches. Make the non-red jewels to be one click away from red. Then use hourglass bonus to turn the non-red to red. The hourglass gives you 5 free clicks without triggering matching, and the 6th will trigger the match. Doing it this way will give you two large reds at once. Repeat this method, though the 2nd & 3rd times you will get one large red and one medium red. Then as you fill in the rest of the jewels, make sure you build up to an "jewel sack" bonus (refills the board) first before filling more jewels. Continue filling-in all 4-in-a rows (white, pink, and yellow), then the rest of the 3-in-a-rows. It took a while! Great game, though!