4 sentences

1. 这颗珍珠圆润而有光泽。

   zhè kē zhēn zhū yuán​rùn ér yǒu guāng​zé.

   This pearl is round and lustrous.

   Source: Dong Chinese Dictionary

2. 这颗珍珠晶莹剔透，色泽圆润。

   zhè kē zhēn​zhū jīng​yíng​tī​tòu, sè​zé yuán​rùn.

   This pearl is crystal clear with a smooth, lustrous color.

   Source: Dong Chinese Dictionary

3. 播音员的嗓音非常圆润。

   bō​yīn​yuán de sǎng​yīn fēi​cháng yuán​rùn.

   The announcer's voice is very mellow.

   Source: Dong Chinese Dictionary

4. 经过多年的磨练，他的为人处世变得圆润了许多。

   jīng​guò duō nián de mó​liàn, tā de wéi​rén chǔ​shì biàn de yuán​rùn le xǔ​duō.

   After years of experience, he has become much more tactful in his dealings with others.

   Source: Dong Chinese Dictionary