there are 3 basic categories of poker chip materials
1) "clay" (paulson, asm, bcc. not really clay)
2) "ceramic" (venerattis, chipco, etc. not really ceramic)
3) injection molded (dice chips, "composite", etc.)
the heaviest chips are invariably cheap injection-molded chips with a metal slug in them. Paulson/ASM/BCC chips that were the casino standard for decades were ~9-10g. Ceramics are a similar weight.
You don't need 14g chips. Slugged chips have a characteristic sound that people associate with cheap chips, so they're actually not preferred.
see the
HPF FAQ for excellent overview information. There have also been extensive threads about chips in the last month or two that are worth searching for.