We did a ring on a necklace chain hung above belly, circles meant girl back and forth meant boy. We did a test where you pee into a cup of baking soda, if it goes fizzy like a soda you just poured, typically means boy, if it did nothing it meant girl. Those were the two test that came out accurate for us.
I did the ring over the belly and this Chinese calendar thing I found on the internet. It went off of your birthday and when you conceived if I remember correctly. But both came out girl and was right.