http://revach.net/article.php?id=448

Section: Tanach   Category: Shir Hashirim
Shir HaShirim: Bnei Yisroel Is As Good As Gold... But Best To Add A Little Silver
Gold symbolizes the Midah of Din. Its roots are in fire which is very useful but if misused it is a most destructive force. Silver symbolizes Chesed which has its roots in water that gives life. Before Hashem created the world each Neshama in Shamayim received the ultimate pleasures. However this pleasure was marred by the fact that it was pure Chesed; undeserved. Hashem created a world of Din to enable the Neshama to earn its reward. He saw however that without a dose of Chesed the world would not survive and the ultimate purpose would not be achieved. Therefore he added a bit of Chesed to the world.

At Har Sinai Bnei Yisroel reached its zenith. We were truly deserving of all of Hashem's love through Din. Nevertheless being as we were still in Olam Hazeh Hashem saw it fit to treat us not only with Din but with Chesed as well just in case...

"Toirei Zahav Naaseh Lach"; Hashem at Har Sinai made us gold jewelry. He treated us with Din and still bestowed upon us all his love. Yet the pasuk adds "Im Nikudos HaKesef"; Hashem added to this beautiful adornment of silver stones because in this world we would not survive very long with pure Din. (based on the Tzror Hamor on Shir HaShirim)