Hextech Annie/Gemstone odds??

So.....I know I had planned on not buying into Rito's scam hextech system but I really wanted the Hextech Annie skin. Figured maybe i'd get lucky and randomly get it in a chest or if not use 10 gemstones. Here's the problem.....After buying about 70+ chest/key's I've only gotten ONE gemstone and no Annie skin. Wth???? ONE gemstone at this rate i'd have to spend close to 1k$$$ on some rigged system to get the skin.