For at følge på Johannes svar fandt jeg en løsning på et forum et sted. Dette regex gør tricket :)
$unicodeRegexp = '([*#0-9](?>\\xEF\\xB8\\x8F)?\\xE2\\x83\\xA3|\\xC2[\\xA9\\xAE]|\\xE2..(\\xF0\\x9F\\x8F[\\xBB-\\xBF])?(?>\\xEF\\xB8\\x8F)?|\\xE3(?>\\x80[\\xB0\\xBD]|\\x8A[\\x97\\x99])(?>\\xEF\\xB8\\x8F)?|\\xF0\\x9F(?>[\\x80-\\x86].(?>\\xEF\\xB8\\x8F)?|\\x87.\\xF0\\x9F\\x87.|..(\\xF0\\x9F\\x8F[\\xBB-\\xBF])?|(((?<zwj>\\xE2\\x80\\x8D)\\xE2\\x9D\\xA4\\xEF\\xB8\\x8F\k<zwj>\\xF0\\x9F..(\k<zwj>\\xF0\\x9F\\x91.)?|(\\xE2\\x80\\x8D\\xF0\\x9F\\x91.){2,3}))?))';