I recently sent a jumbo express box from Thailand to Boston (max. wgt. 25kg) w/ disastrous results. U.S. Customs broke a lot of the contents including most of the most valuable contents: a jade teapot, 3 celadon plates, 2 Japanese porcelain gaiwan. Unwrapped items were not re-wrapped; multi-piece lacquerware was not put together; bags of jewelry etc. were just emptied into the box, etc. (A jade ring is missing)
I think Customs got their blood up by tobacco-related items (1 pipe & many cigar accessories) & by many personal items being included w/ new items. (About 15 years ago I sent books, old shirts, etc. that led to expensive communication by fax, delays, an unmerited tax, & 4 missing items).
Looking at the separated knob of the lid & separated handle of the jade teapot, I imagine some agent angry about the work needed to remove the taped bubble-wrap. I've never had a large work of jade break before. Was the pot violently thrown into the box to smash against the ceramic pieces & lacquerware? Not all of the wrapping was even dumped back into the box; so, on the trip from where it landed to Boston, hard jade was able to bang against unprotected ceramics & lacquerware.
My advice is to allow maximum visibility to discourage agents from thinking something is hidden. Don't fill the space of cups, pots, etc.; leave lids off; don't use clothes for wrapping or padding; don't include personal items; don't include any item that could be seen as drug-related stuff.
From this box: Received in good shape: about $100 worth of stuff at a shipping cost of $250. Survival rate of special items: 25%.