I believe it comes down to two things.
The first being the shape: narrow at the bottom, wide at the top, basically an upside down triangle, lets all the heat out super fast. The old ones were a bit curved at the base but had straight sides.
The second is that while they are made of ceramic I am pretty sure it's not porcelain. Our old ones say "Fine Bone China" but the new ones have nothing on them, that has to be a bad sign!
Do you have good tea cup/mugs??? We both drink tea in mugs not tea cups because honestly there's just not enough tea in a tea cup. I need ideas. Where to find new ones. Ones which hold the heat for longer than two minutes. Ones that are made from something better than the duds we currently have.
I need new cups. Help.