Yahya related to me from Malik from Nafi that Abdullah ibn Umar used to adorn his daughters and slave-girls with gold jewellery and he did not take any zakat from their jewellery.
Malik said, "Anyone who has unminted gold or silver, or gold and silver jewellery which is not used for wearing, must pay zakat on it every year. It is weighed and one-fortieth is taken, unless it falls short of twenty dinars of gold or two hundred dirhams of silver, in which case there is no zakat to pay. Zakat is paid only when jewellery is kept for purposes other than wearing. Bits of gold and silver or broken jewellery which the owner intends to mend to wear are in the same position as goods which are worn by their owner - no zakat has to be paid on them by the owner."
Malik said, "There is no zakat (to pay) on pearls, musk or amber."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ يُحَلِّي بَنَاتِهُ وَجَوَارِيَهُ الذَّهَبَ ثُمَّ لاَ يُخْرِجُ مِنْ حُلِيِّهِنَّ الزَّكَاةَ . قَالَ مَالِكٌ مَنْ كَانَ عِنْدَهُ تِبْرٌ أَوْ حَلْىٌ مِنْ ذَهَبٍ أَوْ فِضَّةٍ لاَ يُنْتَفَعُ بِهِ لِلُبْسٍ فَإِنَّ عَلَيْهِ فِيهِ الزَّكَاةَ فِي كُلِّ عَامٍ يُوزَنُ فَيُؤْخَذُ رُبُعُ عُشْرِهِ إِلاَّ أَنْ يَنْقُصَ مِنْ وَزْنِ عِشْرِينَ دِينَارًا عَيْنًا أَوْ مِائَتَىْ دِرْهَمٍ فَإِنْ نَقَصَ مِنْ ذَلِكَ فَلَيْسَ فِيهِ زَكَاةٌ وَإِنَّمَا تَكُونُ فِيهِ الزَّكَاةُ إِذَا كَانَ إِنَّمَا يُمْسِكُهُ لِغَيْرِ اللُّبْسِ فَأَمَّا التِّبْرُ وَالْحُلِيُّ الْمَكْسُورُ الَّذِي يُرِيدُ أَهْلُهُ إِصْلاَحَهُ وَلُبْسَهُ فَإِنَّمَا هُوَ بِمَنْزِلَةِ الْمَتَاعِ الَّذِي يَكُونُ عِنْدَ أَهْلِهِ فَلَيْسَ عَلَى أَهْلِهِ فِيهِ زَكَاةٌ . قَالَ مَالِكٌ لَيْسَ فِي اللُّؤْلُؤِ وَلاَ فِي الْمِسْكِ وَلاَ الْعَنْبَرِ زَكَاةٌ .